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Anatomy_Gray_2800 | Anatomy_Gray | In the clinic Treatment of head injury Treatment of primary brain injury is extremely limited. Axonal disruption and cellular death are generally irrecoverable. Whenever the brain is injured, like most tissues, it swells. Because the brain is encased within a fixed space (the skull), swelling impairs cerebral function and has two other important effects. First, the swelling compresses the blood supply into the skull, resulting in a physiologically dramatic increase in blood pressure. Second, the cerebral swelling may be diffuse, eventually squeezing the brain and brainstem through the foramen magnum (coning). This compression and disruption of the brainstem may lead to a loss of basic cardiorespiratory function, and death will ensue. Focal cerebral edema may cause one side of the brain to herniate beneath the falx cerebri (falcine herniation). | Anatomy_Gray. In the clinic Treatment of head injury Treatment of primary brain injury is extremely limited. Axonal disruption and cellular death are generally irrecoverable. Whenever the brain is injured, like most tissues, it swells. Because the brain is encased within a fixed space (the skull), swelling impairs cerebral function and has two other important effects. First, the swelling compresses the blood supply into the skull, resulting in a physiologically dramatic increase in blood pressure. Second, the cerebral swelling may be diffuse, eventually squeezing the brain and brainstem through the foramen magnum (coning). This compression and disruption of the brainstem may lead to a loss of basic cardiorespiratory function, and death will ensue. Focal cerebral edema may cause one side of the brain to herniate beneath the falx cerebri (falcine herniation). |
Anatomy_Gray_2801 | Anatomy_Gray | Simple measures to prevent the swelling include hyperventilation (which alters the intracerebral acid–base balance and decreases swelling) and intravenous corticosteroids (though their action is often delayed). Extracerebral hematoma may be removed surgically. The outcome of patients with head injury depends on how the secondary injury is managed. Even with a severe primary injury, patients may recover to lead a normal life. In the clinic | Anatomy_Gray. Simple measures to prevent the swelling include hyperventilation (which alters the intracerebral acid–base balance and decreases swelling) and intravenous corticosteroids (though their action is often delayed). Extracerebral hematoma may be removed surgically. The outcome of patients with head injury depends on how the secondary injury is managed. Even with a severe primary injury, patients may recover to lead a normal life. In the clinic |
Anatomy_Gray_2802 | Anatomy_Gray | The outcome of patients with head injury depends on how the secondary injury is managed. Even with a severe primary injury, patients may recover to lead a normal life. In the clinic The skull is a closed bony compartment, and the brain and cerebrospinal fluid are maintained physiologically within a narrow intracranial pressure range. Any new space-occupying lesion, such as a hematoma, an injury that leads to brain swelling, or a brain tumor, can increase intracranial pressure and compress the brain. In severe cases, the brain may be squeezed down into the foramen magnum, giving it a cone shape, termed cerebral herniation, or “coning.” This may in turn compress the brainstem and upper cervical spinal cord, which can be fatal. | Anatomy_Gray. The outcome of patients with head injury depends on how the secondary injury is managed. Even with a severe primary injury, patients may recover to lead a normal life. In the clinic The skull is a closed bony compartment, and the brain and cerebrospinal fluid are maintained physiologically within a narrow intracranial pressure range. Any new space-occupying lesion, such as a hematoma, an injury that leads to brain swelling, or a brain tumor, can increase intracranial pressure and compress the brain. In severe cases, the brain may be squeezed down into the foramen magnum, giving it a cone shape, termed cerebral herniation, or “coning.” This may in turn compress the brainstem and upper cervical spinal cord, which can be fatal. |
Anatomy_Gray_2803 | Anatomy_Gray | Congenital herniation or coning of the cerebellar tonsils through the foramen magnum can also occur if the posterior fossa is too small, a condition known as Chiari I malformation (Fig. 8.52). This often causes no problems in childhood and may only start causing symptoms in adulthood. In the clinic In the clinic Overview of cranial nerves Afferent—Trigeminal nerve (CN V) Efferent—Facial nerve (CN VII) Afferent—Glossopharyngeal nerve (CN IX) Efferent—Vagus nerve (CN X) Afferent—optic nerve (CN II) Efferent—oculomotor nerve (CN III) Fig. 8.55 Overview of cranial nerves. | Anatomy_Gray. Congenital herniation or coning of the cerebellar tonsils through the foramen magnum can also occur if the posterior fossa is too small, a condition known as Chiari I malformation (Fig. 8.52). This often causes no problems in childhood and may only start causing symptoms in adulthood. In the clinic In the clinic Overview of cranial nerves Afferent—Trigeminal nerve (CN V) Efferent—Facial nerve (CN VII) Afferent—Glossopharyngeal nerve (CN IX) Efferent—Vagus nerve (CN X) Afferent—optic nerve (CN II) Efferent—oculomotor nerve (CN III) Fig. 8.55 Overview of cranial nerves. |
Anatomy_Gray_2804 | Anatomy_Gray | Glossopharyngeal nerve [IX]Special sensory – taste (posterior 1/3 of tongue)Somatic sensory – posterior 1/3 of tongue, oropharynx,palatine tonsil, middle ear, pharyngotympanic tube, andmastoid air cellsBranchial motor – stylopharyngeusVisceral motor – (parasympathetic) – secretomotor to theparotid glandVisceral sensory – from carotid body and sinusFacial nerve [VII] Branchial motor – all muscles of facial expression, andstapedius, stylohyoid, and posterior belly of digastricEfferent (motor) fibersV3V3V2V1Afferent (sensory) fibersFacial nerve [VII] (intermediate nerve)Special sensory – taste (anterior 2/3 of tongue)Somatic sensory – part of external acoustic meatus anddeeper parts of auricleVisceral motor (parasympathetic) – secretomotor to allsalivary glands except for parotid gland; all mucous glandsassociated with the oral and nasal cavities; lacrimal glandVestibulocochlear nerve [VIII]Special sensory – hearing and balanceOlfactory nerve [I]Special sensory – smellOptic nerve | Anatomy_Gray. Glossopharyngeal nerve [IX]Special sensory – taste (posterior 1/3 of tongue)Somatic sensory – posterior 1/3 of tongue, oropharynx,palatine tonsil, middle ear, pharyngotympanic tube, andmastoid air cellsBranchial motor – stylopharyngeusVisceral motor – (parasympathetic) – secretomotor to theparotid glandVisceral sensory – from carotid body and sinusFacial nerve [VII] Branchial motor – all muscles of facial expression, andstapedius, stylohyoid, and posterior belly of digastricEfferent (motor) fibersV3V3V2V1Afferent (sensory) fibersFacial nerve [VII] (intermediate nerve)Special sensory – taste (anterior 2/3 of tongue)Somatic sensory – part of external acoustic meatus anddeeper parts of auricleVisceral motor (parasympathetic) – secretomotor to allsalivary glands except for parotid gland; all mucous glandsassociated with the oral and nasal cavities; lacrimal glandVestibulocochlear nerve [VIII]Special sensory – hearing and balanceOlfactory nerve [I]Special sensory – smellOptic nerve |
Anatomy_Gray_2805 | Anatomy_Gray | all mucous glandsassociated with the oral and nasal cavities; lacrimal glandVestibulocochlear nerve [VIII]Special sensory – hearing and balanceOlfactory nerve [I]Special sensory – smellOptic nerve [II]Special sensory – visionTrigeminal nerve [V] sensory rootSomatic sensory – eyes, orbital contents, face, sinuses, teeth, nasal cavities, oral cavity, anterior 2/3 of tongue, nasopharynx, dura, anterior part of external ear,and part of external acoustic meatusTrigeminal nerve [V] motor rootBranchial motor – the four muscles of mastication(medial pterygoid, lateral pterygoid, masseter, temporalis)and mylohyoid, anterior belly of digastric, tensor tympani,and tensor veli palatiniOculomotor nerve [III]Somatic motor – five extra-ocular muscles (superior rectus, medial rectus,inferior oblique, inferior rectus, and levator palpebrae superioris)Visceral motor – ciliary muscles and sphincter pupillae musclesTrochlear nerve [IV]Somatic motor – one extra-ocularmuscle (superior oblique)Abducent | Anatomy_Gray. all mucous glandsassociated with the oral and nasal cavities; lacrimal glandVestibulocochlear nerve [VIII]Special sensory – hearing and balanceOlfactory nerve [I]Special sensory – smellOptic nerve [II]Special sensory – visionTrigeminal nerve [V] sensory rootSomatic sensory – eyes, orbital contents, face, sinuses, teeth, nasal cavities, oral cavity, anterior 2/3 of tongue, nasopharynx, dura, anterior part of external ear,and part of external acoustic meatusTrigeminal nerve [V] motor rootBranchial motor – the four muscles of mastication(medial pterygoid, lateral pterygoid, masseter, temporalis)and mylohyoid, anterior belly of digastric, tensor tympani,and tensor veli palatiniOculomotor nerve [III]Somatic motor – five extra-ocular muscles (superior rectus, medial rectus,inferior oblique, inferior rectus, and levator palpebrae superioris)Visceral motor – ciliary muscles and sphincter pupillae musclesTrochlear nerve [IV]Somatic motor – one extra-ocularmuscle (superior oblique)Abducent |
Anatomy_Gray_2806 | Anatomy_Gray | inferior rectus, and levator palpebrae superioris)Visceral motor – ciliary muscles and sphincter pupillae musclesTrochlear nerve [IV]Somatic motor – one extra-ocularmuscle (superior oblique)Abducent nerve [VI]Somatic motor – one extra-ocularmuscle (lateral rectus)Hypoglossal nerve [XII]Somatic motor – all muscles of thetongue except palatoglossusAccessory nerve [XI]Branchial motor – sternocleidomastoidand trapeziusVagus nerve [X]Somatic sensory – larynx, laryngopharynx, deeper parts ofauricle, and part of external acoustic meatusSpecial sensory – taste from epiglottis and pharynxBranchial motor – all muscles of pharynx except for stylopharyngeus; all muscles of the soft palate except for tensor veli palatini, all intrinsic muscles of larynxVisceral motor – (parasympathetic) – thoracic viscera andabdominal viscera to end of midgutVisceral sensory – thoracic viscera and abdominal viscerato end of midgut, chemoand baroreceptors(and in some cases carotid body) | Anatomy_Gray. inferior rectus, and levator palpebrae superioris)Visceral motor – ciliary muscles and sphincter pupillae musclesTrochlear nerve [IV]Somatic motor – one extra-ocularmuscle (superior oblique)Abducent nerve [VI]Somatic motor – one extra-ocularmuscle (lateral rectus)Hypoglossal nerve [XII]Somatic motor – all muscles of thetongue except palatoglossusAccessory nerve [XI]Branchial motor – sternocleidomastoidand trapeziusVagus nerve [X]Somatic sensory – larynx, laryngopharynx, deeper parts ofauricle, and part of external acoustic meatusSpecial sensory – taste from epiglottis and pharynxBranchial motor – all muscles of pharynx except for stylopharyngeus; all muscles of the soft palate except for tensor veli palatini, all intrinsic muscles of larynxVisceral motor – (parasympathetic) – thoracic viscera andabdominal viscera to end of midgutVisceral sensory – thoracic viscera and abdominal viscerato end of midgut, chemoand baroreceptors(and in some cases carotid body) |
Anatomy_Gray_2807 | Anatomy_Gray | In the clinic Facelift surgery (rhytidectomy) aims to lift up and pull back the skin in the lower half of the face and neck to make the face more taught. Careful placement of the incisions is important to ensure there is no skin or facial distortion and to avoid hair loss. The commonest incisions are placed in the temporal region on each side, extending to the helices of the ears, then tracking behind the tragus, around the earlobes, and then to the occiput. | Anatomy_Gray. In the clinic Facelift surgery (rhytidectomy) aims to lift up and pull back the skin in the lower half of the face and neck to make the face more taught. Careful placement of the incisions is important to ensure there is no skin or facial distortion and to avoid hair loss. The commonest incisions are placed in the temporal region on each side, extending to the helices of the ears, then tracking behind the tragus, around the earlobes, and then to the occiput. |
Anatomy_Gray_2808 | Anatomy_Gray | Botox is derived from the toxin produced by the bacterium Clostridium botulinum, which blocks neuromuscular junctions resulting in muscle relaxation. It is used in many therapies including strabismus (crossed eyes) where it is injected into extra-ocular muscles. Its injection is also used to treat uncontrolled blinking (blepharospasm), spastic muscle conditions, and overactive bladder disorders, as well as to relax facial muscles to improve the cosmetic appearances of lines and wrinkles and to treat patients with excessive sweating (hyperhidrosis). In the clinic The parotid gland is the largest of the paired salivary glands and is enclosed within the split investing layer of deep cervical fascia. The parotid gland produces a watery saliva and salivary amylase, which are necessary for food bolus formation, oral digestion, and smooth passage of the bolus into the upper gastrointestinal tract. Tumors of the parotid gland | Anatomy_Gray. Botox is derived from the toxin produced by the bacterium Clostridium botulinum, which blocks neuromuscular junctions resulting in muscle relaxation. It is used in many therapies including strabismus (crossed eyes) where it is injected into extra-ocular muscles. Its injection is also used to treat uncontrolled blinking (blepharospasm), spastic muscle conditions, and overactive bladder disorders, as well as to relax facial muscles to improve the cosmetic appearances of lines and wrinkles and to treat patients with excessive sweating (hyperhidrosis). In the clinic The parotid gland is the largest of the paired salivary glands and is enclosed within the split investing layer of deep cervical fascia. The parotid gland produces a watery saliva and salivary amylase, which are necessary for food bolus formation, oral digestion, and smooth passage of the bolus into the upper gastrointestinal tract. Tumors of the parotid gland |
Anatomy_Gray_2809 | Anatomy_Gray | Tumors of the parotid gland The commonest tumors of the parotid gland (Fig. 8.63) are benign and typically involve the more superficial part of the gland. These include pleomorphic adenoma and adenolymphoma. Their importance is in relation to their anatomical position. The relationship of any tumor to the branches of the facial nerve [VII] must be defined because resection of the tumor may damage the nerve. It is not uncommon for stones to develop within the parotid gland. They typically occur within the main confluence of the ducts and within the main parotid duct. The patient usually complains of intense pain when salivating and tends to avoid foods that produce this symptom. The pain can be easily reproduced in the clinic by squirting lemon juice into the patient’s mouth. | Anatomy_Gray. Tumors of the parotid gland The commonest tumors of the parotid gland (Fig. 8.63) are benign and typically involve the more superficial part of the gland. These include pleomorphic adenoma and adenolymphoma. Their importance is in relation to their anatomical position. The relationship of any tumor to the branches of the facial nerve [VII] must be defined because resection of the tumor may damage the nerve. It is not uncommon for stones to develop within the parotid gland. They typically occur within the main confluence of the ducts and within the main parotid duct. The patient usually complains of intense pain when salivating and tends to avoid foods that produce this symptom. The pain can be easily reproduced in the clinic by squirting lemon juice into the patient’s mouth. |
Anatomy_Gray_2810 | Anatomy_Gray | Surgery depends upon where the stone is. If it is within the anterior aspect of the duct, a simple incision in the buccal mucosa with a sphincterotomy may allow removal. If the stone is farther back within the main duct, complete gland excision may be necessary. In the clinic The complexity of the facial nerve [VII] is demonstrated by the different pathological processes and sites at which these processes occur. | Anatomy_Gray. Surgery depends upon where the stone is. If it is within the anterior aspect of the duct, a simple incision in the buccal mucosa with a sphincterotomy may allow removal. If the stone is farther back within the main duct, complete gland excision may be necessary. In the clinic The complexity of the facial nerve [VII] is demonstrated by the different pathological processes and sites at which these processes occur. |
Anatomy_Gray_2811 | Anatomy_Gray | In the clinic The complexity of the facial nerve [VII] is demonstrated by the different pathological processes and sites at which these processes occur. The facial nerve [VII] is formed from the nuclei within the brainstem emerging at the junction of the pons and the medulla. It enters the internal acoustic meatus, passes to the geniculate ganglion (which gives rise to further branches), and emerges from the skull base after a complex course within the temporal bone, leaving through the stylomastoid foramen. It enters the parotid gland and gives rise to five terminal groups of branches that supply muscles in the face and a number of additional branches that supply deeper or more posterior muscles. A series of lesions may affect the nerve along its course, and it is possible, with good clinical expertise, to determine the exact site of the lesion in relation to the course of the nerve. | Anatomy_Gray. In the clinic The complexity of the facial nerve [VII] is demonstrated by the different pathological processes and sites at which these processes occur. The facial nerve [VII] is formed from the nuclei within the brainstem emerging at the junction of the pons and the medulla. It enters the internal acoustic meatus, passes to the geniculate ganglion (which gives rise to further branches), and emerges from the skull base after a complex course within the temporal bone, leaving through the stylomastoid foramen. It enters the parotid gland and gives rise to five terminal groups of branches that supply muscles in the face and a number of additional branches that supply deeper or more posterior muscles. A series of lesions may affect the nerve along its course, and it is possible, with good clinical expertise, to determine the exact site of the lesion in relation to the course of the nerve. |
Anatomy_Gray_2812 | Anatomy_Gray | A primary brainstem lesion affecting the motor nucleus of the facial nerve [VII] would lead to ipsilateral (same side) weakness of the whole face. However, because the upper part of the nucleus receives motor input from the left and right cerebral hemispheres a lesion occurring above the nucleus leads to contralateral lower facial weakness. In this example, motor innervation to the upper face is spared because the upper part of the nucleus receives input from both hemispheres. Preservation and loss of the special functions are determined by the extent of the lesion. Lesions at and around the geniculate ganglion Typically lesions at and around the geniculate ganglion are accompanied by loss of motor function on the whole of the ipsilateral (same) side of the face. Taste to the anterior two-thirds of the tongue, lacrimation, and some salivation also are likely to be affected because the lesion is proximal to the greater petrosal and chorda tympani branches of the nerve. | Anatomy_Gray. A primary brainstem lesion affecting the motor nucleus of the facial nerve [VII] would lead to ipsilateral (same side) weakness of the whole face. However, because the upper part of the nucleus receives motor input from the left and right cerebral hemispheres a lesion occurring above the nucleus leads to contralateral lower facial weakness. In this example, motor innervation to the upper face is spared because the upper part of the nucleus receives input from both hemispheres. Preservation and loss of the special functions are determined by the extent of the lesion. Lesions at and around the geniculate ganglion Typically lesions at and around the geniculate ganglion are accompanied by loss of motor function on the whole of the ipsilateral (same) side of the face. Taste to the anterior two-thirds of the tongue, lacrimation, and some salivation also are likely to be affected because the lesion is proximal to the greater petrosal and chorda tympani branches of the nerve. |
Anatomy_Gray_2813 | Anatomy_Gray | Lesions at and around the stylomastoid foramen Lesions at and around the stylomastoid foramen are the commonest abnormality of the facial nerve [VII] and usually result from a viral inflammation of the nerve within the bony canal before exiting through the stylomastoid foramen. Typically the patient has an ipsilateral loss of motor function of the whole side of the face. Not only does this produce an unusual appearance, but it also complicates chewing of food. Lacrimation and taste may not be affected if the lesion remains distal to the greater petrosal and chorda tympani branches that originate deep in the temporal bone. In the clinic Trigeminal neuralgia (tic douloureux) is a complex sensory disorder of the sensory root of the trigeminal nerve. Typically the pain is in the region of the mandibular [V3] and maxillary [V2] nerves, and is usually of sudden onset, is excruciating in nature, and may be triggered by touching a sensitive region of skin. | Anatomy_Gray. Lesions at and around the stylomastoid foramen Lesions at and around the stylomastoid foramen are the commonest abnormality of the facial nerve [VII] and usually result from a viral inflammation of the nerve within the bony canal before exiting through the stylomastoid foramen. Typically the patient has an ipsilateral loss of motor function of the whole side of the face. Not only does this produce an unusual appearance, but it also complicates chewing of food. Lacrimation and taste may not be affected if the lesion remains distal to the greater petrosal and chorda tympani branches that originate deep in the temporal bone. In the clinic Trigeminal neuralgia (tic douloureux) is a complex sensory disorder of the sensory root of the trigeminal nerve. Typically the pain is in the region of the mandibular [V3] and maxillary [V2] nerves, and is usually of sudden onset, is excruciating in nature, and may be triggered by touching a sensitive region of skin. |
Anatomy_Gray_2814 | Anatomy_Gray | The etiology of trigeminal neuralgia is unknown, although anomalous blood vessels lying adjacent to the sensory route of the maxillary [V2] and mandibular [V3] nerves may be involved. If symptoms persist and are unresponsive to medical care, surgical exploration of the trigeminal nerve (which is not without risk) may be necessary to remove any aberrant vessels. In the clinic The scalp has an extremely rich blood supply from the external carotid arteries, so lacerations of the scalp tend to bleed profusely. Importantly, scalp bleeding is predominantly arterial, because of two reasons. First, in the erect position the venous pressure is extremely low. Second, the vessels do not retract and close when lacerated because the connective tissue in which they are found holds them open. In the clinic | Anatomy_Gray. The etiology of trigeminal neuralgia is unknown, although anomalous blood vessels lying adjacent to the sensory route of the maxillary [V2] and mandibular [V3] nerves may be involved. If symptoms persist and are unresponsive to medical care, surgical exploration of the trigeminal nerve (which is not without risk) may be necessary to remove any aberrant vessels. In the clinic The scalp has an extremely rich blood supply from the external carotid arteries, so lacerations of the scalp tend to bleed profusely. Importantly, scalp bleeding is predominantly arterial, because of two reasons. First, in the erect position the venous pressure is extremely low. Second, the vessels do not retract and close when lacerated because the connective tissue in which they are found holds them open. In the clinic |
Anatomy_Gray_2815 | Anatomy_Gray | In the clinic Fractures of the orbit are not uncommon and may involve the orbital margins with extension into the maxilla, frontal, and zygomatic bones. These fractures are often part of complex facial fractures. Fractures within the orbit frequently occur within the floor and the medial wall; however, superior and lateral wall fractures also occur. Inferior orbital floor fractures are one of the commonest types of injuries. These fractures may drag the inferior oblique muscle and associated tissues into the fracture line. In these instances, patients may have upward gaze failure (upward gaze diplopia) in the affected eye. Medial wall fractures characteristically show air within the orbit in radiographs. This is due to fracture of the ethmoidal labyrinth, permitting direct continuity between the orbit and the ethmoidal paranasal sinuses. Occasionally, patients feel a full sensation within the orbit when blowing the nose. In the clinic | Anatomy_Gray. In the clinic Fractures of the orbit are not uncommon and may involve the orbital margins with extension into the maxilla, frontal, and zygomatic bones. These fractures are often part of complex facial fractures. Fractures within the orbit frequently occur within the floor and the medial wall; however, superior and lateral wall fractures also occur. Inferior orbital floor fractures are one of the commonest types of injuries. These fractures may drag the inferior oblique muscle and associated tissues into the fracture line. In these instances, patients may have upward gaze failure (upward gaze diplopia) in the affected eye. Medial wall fractures characteristically show air within the orbit in radiographs. This is due to fracture of the ethmoidal labyrinth, permitting direct continuity between the orbit and the ethmoidal paranasal sinuses. Occasionally, patients feel a full sensation within the orbit when blowing the nose. In the clinic |
Anatomy_Gray_2816 | Anatomy_Gray | In the clinic Horner’s syndrome is caused by any lesion that leads to a loss of sympathetic function in the head. It is characterized by three typical features: pupillary constriction due to paralysis of the dilator pupillae muscle, partial ptosis (drooping of the upper eyelid) due to paralysis of the superior tarsal muscle, and absence of sweating on the ipsilateral side of the face and the neck due to absence of innervation of the sweat glands. Secondary changes may also include: ipsilateral vasodilation due to loss of the normal sympathetic control of the subcutaneous blood vessels, and enophthalmos (sinking of the eye)—believed to result from paralysis of the orbitalis muscle, although this is an uncommon feature of Horner’s syndrome. The orbitalis muscle spans the inferior orbital fissure and helps maintain the forward position of orbital contents. | Anatomy_Gray. In the clinic Horner’s syndrome is caused by any lesion that leads to a loss of sympathetic function in the head. It is characterized by three typical features: pupillary constriction due to paralysis of the dilator pupillae muscle, partial ptosis (drooping of the upper eyelid) due to paralysis of the superior tarsal muscle, and absence of sweating on the ipsilateral side of the face and the neck due to absence of innervation of the sweat glands. Secondary changes may also include: ipsilateral vasodilation due to loss of the normal sympathetic control of the subcutaneous blood vessels, and enophthalmos (sinking of the eye)—believed to result from paralysis of the orbitalis muscle, although this is an uncommon feature of Horner’s syndrome. The orbitalis muscle spans the inferior orbital fissure and helps maintain the forward position of orbital contents. |
Anatomy_Gray_2817 | Anatomy_Gray | The orbitalis muscle spans the inferior orbital fissure and helps maintain the forward position of orbital contents. The commonest cause for Horner’s syndrome is a tumor eroding the cervicothoracic ganglion, which is typically an apical lung tumor. A surgically induced Horner’s syndrome may be necessary for patients who suffer severe hyperhidrosis (sweating). This often debilitating condition may be so severe that patients are confined to their home for fear of embarrassment. Treatment is relatively straightforward. The patient is anesthetized and a bifurcate endotracheal tube is placed into the left and right main bronchi. A small incision is made in the intercostal space on the appropriate side, and a surgically induced pneumothorax is created. The patient is ventilated through the contralateral lung. | Anatomy_Gray. The orbitalis muscle spans the inferior orbital fissure and helps maintain the forward position of orbital contents. The commonest cause for Horner’s syndrome is a tumor eroding the cervicothoracic ganglion, which is typically an apical lung tumor. A surgically induced Horner’s syndrome may be necessary for patients who suffer severe hyperhidrosis (sweating). This often debilitating condition may be so severe that patients are confined to their home for fear of embarrassment. Treatment is relatively straightforward. The patient is anesthetized and a bifurcate endotracheal tube is placed into the left and right main bronchi. A small incision is made in the intercostal space on the appropriate side, and a surgically induced pneumothorax is created. The patient is ventilated through the contralateral lung. |
Anatomy_Gray_2818 | Anatomy_Gray | Using an endoscope the apex of the thoracic cavity can be viewed from inside and the cervicothoracic ganglion readily identified. Obliterative techniques include thermocoagulation and surgical excision. After the ganglion has been destroyed, the endoscope is removed, the lung is reinflated, and the small hole is sutured. In the clinic Examination of the eye Examination of the eye includes assessment of the visual capabilities, the extrinsic musculature and its function, and disease processes that may affect the eye in isolation or as part of the systemic process. Examination of the eye includes tests for visual acuity, astigmatism, visual fields, and color interpretation (to exclude color blindness) in a variety of circumstances. The physician also assesses the retina, the optic nerve and its coverings, the lens, and the cornea. The extrinsic muscles are supplied by the abducent nerve [VI], the trochlear nerve [IV], and the oculomotor nerve [III]. | Anatomy_Gray. Using an endoscope the apex of the thoracic cavity can be viewed from inside and the cervicothoracic ganglion readily identified. Obliterative techniques include thermocoagulation and surgical excision. After the ganglion has been destroyed, the endoscope is removed, the lung is reinflated, and the small hole is sutured. In the clinic Examination of the eye Examination of the eye includes assessment of the visual capabilities, the extrinsic musculature and its function, and disease processes that may affect the eye in isolation or as part of the systemic process. Examination of the eye includes tests for visual acuity, astigmatism, visual fields, and color interpretation (to exclude color blindness) in a variety of circumstances. The physician also assesses the retina, the optic nerve and its coverings, the lens, and the cornea. The extrinsic muscles are supplied by the abducent nerve [VI], the trochlear nerve [IV], and the oculomotor nerve [III]. |
Anatomy_Gray_2819 | Anatomy_Gray | The extrinsic muscles are supplied by the abducent nerve [VI], the trochlear nerve [IV], and the oculomotor nerve [III]. The extrinsic muscles work synergistically to provide appropriate and conjugate eye movement: lateral rectus—abducent nerve [VI], superior oblique—trochlear nerve [IV], and remainder—oculomotor nerve [III]. The eye may be affected in systemic diseases. Diabetes mellitus typically affects the eye and may cause cataracts, macular disease, and retinal hemorrhage, all impairing vision. Occasionally unilateral paralysis of the extra-ocular muscles occurs and is due to brainstem injury or direct nerve injury, which may be associated with tumor compression or trauma. The paralysis of a muscle is easily demonstrated when the patient attempts to move the eye in the direction associated with normal action of that muscle. Typically the patient complains of double vision (diplopia). Loss of innervation of the muscles around the eye | Anatomy_Gray. The extrinsic muscles are supplied by the abducent nerve [VI], the trochlear nerve [IV], and the oculomotor nerve [III]. The extrinsic muscles work synergistically to provide appropriate and conjugate eye movement: lateral rectus—abducent nerve [VI], superior oblique—trochlear nerve [IV], and remainder—oculomotor nerve [III]. The eye may be affected in systemic diseases. Diabetes mellitus typically affects the eye and may cause cataracts, macular disease, and retinal hemorrhage, all impairing vision. Occasionally unilateral paralysis of the extra-ocular muscles occurs and is due to brainstem injury or direct nerve injury, which may be associated with tumor compression or trauma. The paralysis of a muscle is easily demonstrated when the patient attempts to move the eye in the direction associated with normal action of that muscle. Typically the patient complains of double vision (diplopia). Loss of innervation of the muscles around the eye |
Anatomy_Gray_2820 | Anatomy_Gray | Loss of innervation of the muscles around the eye Loss of innervation of the orbicularis oculi by the facial nerve [VII] causes an inability to close the eyelids tightly, allowing the lower eyelid to droop away causing spillage of tears. This loss of tears allows drying of the conjunctiva, which may ulcerate, so allowing secondary infection. Loss of innervation of the levator palpebrae superioris by oculomotor nerve [III] damage causes an inability of the superior eyelid to elevate, producing a complete ptosis. Usually, oculomotor nerve [III] damage is caused by severe head injury. Loss of innervation of the superior tarsal muscle by sympathetic fibers causes a constant partial ptosis. Any lesion along the sympathetic trunk can induce this. An apical pulmonary malignancy should always be suspected because the ptosis may be part of Horner’s syndrome (see “In the clinic” on p. 920). In the clinic The “H-test” | Anatomy_Gray. Loss of innervation of the muscles around the eye Loss of innervation of the orbicularis oculi by the facial nerve [VII] causes an inability to close the eyelids tightly, allowing the lower eyelid to droop away causing spillage of tears. This loss of tears allows drying of the conjunctiva, which may ulcerate, so allowing secondary infection. Loss of innervation of the levator palpebrae superioris by oculomotor nerve [III] damage causes an inability of the superior eyelid to elevate, producing a complete ptosis. Usually, oculomotor nerve [III] damage is caused by severe head injury. Loss of innervation of the superior tarsal muscle by sympathetic fibers causes a constant partial ptosis. Any lesion along the sympathetic trunk can induce this. An apical pulmonary malignancy should always be suspected because the ptosis may be part of Horner’s syndrome (see “In the clinic” on p. 920). In the clinic The “H-test” |
Anatomy_Gray_2821 | Anatomy_Gray | In the clinic The “H-test” A simple “formula” for remembering the nerves that innervate the extraocular muscles is “LR6SO4 and all the rest are 3” (lateral rectus [VI], superior oblique [IV], all the rest including levator palpebrae superioris are [III]). The function of all extrinsic muscles and their nerves [III, IV, VI] that move the eyeball in both orbits can all easily be tested at the same time by having the patient track, without moving his or her head, an object such as the tip of a pen or a finger moved in an “H” pattern—starting from the midline between the two eyes (Fig. 8.98). In the clinic Intraocular pressure will rise if the normal cycle of aqueous humor fluid production and absorption is disturbed so that the amount of fluid increases. This condition is glaucoma and can lead to a variety of visual problems including blindness, which results from compression of the retina and its blood supply. In the clinic | Anatomy_Gray. In the clinic The “H-test” A simple “formula” for remembering the nerves that innervate the extraocular muscles is “LR6SO4 and all the rest are 3” (lateral rectus [VI], superior oblique [IV], all the rest including levator palpebrae superioris are [III]). The function of all extrinsic muscles and their nerves [III, IV, VI] that move the eyeball in both orbits can all easily be tested at the same time by having the patient track, without moving his or her head, an object such as the tip of a pen or a finger moved in an “H” pattern—starting from the midline between the two eyes (Fig. 8.98). In the clinic Intraocular pressure will rise if the normal cycle of aqueous humor fluid production and absorption is disturbed so that the amount of fluid increases. This condition is glaucoma and can lead to a variety of visual problems including blindness, which results from compression of the retina and its blood supply. In the clinic |
Anatomy_Gray_2822 | Anatomy_Gray | In the clinic With increasing age and in certain disease states the lens of the eye becomes opaque. Increasing opacity results in increasing visual impairment. A common operation is excision of the cloudy lens and replacement with a new man-made lens. In the clinic Direct visualization of the postremal (vitreous) chamber of the eye is possible in most clinical settings. It is achieved using an ophthalmoscope, which is a small battery-operated light with a tiny lens that allows direct visualization of the postremal (vitreous) chamber and the posterior wall of the eye through the pupil and the lens. It is sometimes necessary to place a drug directly onto the eye to dilate the pupil for better visualization. The optic nerve, observed as the optic disc, is easily seen. The typical four branches of the central retinal artery and the fovea are also seen. | Anatomy_Gray. In the clinic With increasing age and in certain disease states the lens of the eye becomes opaque. Increasing opacity results in increasing visual impairment. A common operation is excision of the cloudy lens and replacement with a new man-made lens. In the clinic Direct visualization of the postremal (vitreous) chamber of the eye is possible in most clinical settings. It is achieved using an ophthalmoscope, which is a small battery-operated light with a tiny lens that allows direct visualization of the postremal (vitreous) chamber and the posterior wall of the eye through the pupil and the lens. It is sometimes necessary to place a drug directly onto the eye to dilate the pupil for better visualization. The optic nerve, observed as the optic disc, is easily seen. The typical four branches of the central retinal artery and the fovea are also seen. |
Anatomy_Gray_2823 | Anatomy_Gray | The optic nerve, observed as the optic disc, is easily seen. The typical four branches of the central retinal artery and the fovea are also seen. Using ophthalmoscopy the physician can look for diseases of the optic nerve, vascular abnormalities, and changes within the retina (Fig. 8.109). In the clinic High-definition optical coherence tomography (HD-OCT) (Fig. 8.111) is a procedure used to obtain subsurface images of translucent or opaque materials. It is similar to ultrasound, except that it uses light instead of sound to produce high-resolution cross-sectional images. It is especially useful in the diagnosis and management of optic nerve and retinal diseases. An epiretinal membrane (Fig. 8.112) is a thin sheet of fibrous tissue that develops on the surface of the retina in the area of the macula and can cause visual problems. If the visual problems are significant, surgical removal of the membrane may be necessary. In the clinic | Anatomy_Gray. The optic nerve, observed as the optic disc, is easily seen. The typical four branches of the central retinal artery and the fovea are also seen. Using ophthalmoscopy the physician can look for diseases of the optic nerve, vascular abnormalities, and changes within the retina (Fig. 8.109). In the clinic High-definition optical coherence tomography (HD-OCT) (Fig. 8.111) is a procedure used to obtain subsurface images of translucent or opaque materials. It is similar to ultrasound, except that it uses light instead of sound to produce high-resolution cross-sectional images. It is especially useful in the diagnosis and management of optic nerve and retinal diseases. An epiretinal membrane (Fig. 8.112) is a thin sheet of fibrous tissue that develops on the surface of the retina in the area of the macula and can cause visual problems. If the visual problems are significant, surgical removal of the membrane may be necessary. In the clinic |
Anatomy_Gray_2824 | Anatomy_Gray | In the clinic The eustachian tube links the middle ear and pharynx and balances the pressure between the outer and middle ear. Colds and allergies, particularly in children, can result in swelling of the lining of the eustachian tube, which can then impair normal drainage of fluid from the middle ear. The fluid then builds up behind the tympanic membrane, providing an attractive environment for bacteria and viruses to grow and cause otitis media. Left untreated, otitis media can lead to perforation of the tympanic membrane, hearing loss, meningitis, and brain abscess. In the clinic Examination of the ear The ear comprises three components—the external, middle, and internal ear. Clinical examination is carried out to assess hearing and balance. Further examination involves use of an otoscope or other imaging techniques. | Anatomy_Gray. In the clinic The eustachian tube links the middle ear and pharynx and balances the pressure between the outer and middle ear. Colds and allergies, particularly in children, can result in swelling of the lining of the eustachian tube, which can then impair normal drainage of fluid from the middle ear. The fluid then builds up behind the tympanic membrane, providing an attractive environment for bacteria and viruses to grow and cause otitis media. Left untreated, otitis media can lead to perforation of the tympanic membrane, hearing loss, meningitis, and brain abscess. In the clinic Examination of the ear The ear comprises three components—the external, middle, and internal ear. Clinical examination is carried out to assess hearing and balance. Further examination involves use of an otoscope or other imaging techniques. |
Anatomy_Gray_2825 | Anatomy_Gray | Clinical examination is carried out to assess hearing and balance. Further examination involves use of an otoscope or other imaging techniques. The external ear is easily examined. The external acoustic meatus and the tympanic membrane require otoscopic examination (Fig. 8.118B). An otoscope is a device through which light can be shone and the image magnified to inspect the external acoustic meatus and the tympanic membrane. The examination begins by grasping the posterosuperior aspect of the ear and gently retracting it to straighten the external auditory meatus. The normal tympanic membrane is relatively translucent and has a gray–reddish tinge. The handle of the malleus is visible near the center of the membrane. In the 5 o’clock position a cone of light is always demonstrated. The middle ear is investigated by CT and MRI to visualize the malleus, incus, and stapes. The relationship of these bones to the middle ear cavity is determined and any masses identified. | Anatomy_Gray. Clinical examination is carried out to assess hearing and balance. Further examination involves use of an otoscope or other imaging techniques. The external ear is easily examined. The external acoustic meatus and the tympanic membrane require otoscopic examination (Fig. 8.118B). An otoscope is a device through which light can be shone and the image magnified to inspect the external acoustic meatus and the tympanic membrane. The examination begins by grasping the posterosuperior aspect of the ear and gently retracting it to straighten the external auditory meatus. The normal tympanic membrane is relatively translucent and has a gray–reddish tinge. The handle of the malleus is visible near the center of the membrane. In the 5 o’clock position a cone of light is always demonstrated. The middle ear is investigated by CT and MRI to visualize the malleus, incus, and stapes. The relationship of these bones to the middle ear cavity is determined and any masses identified. |
Anatomy_Gray_2826 | Anatomy_Gray | The middle ear is investigated by CT and MRI to visualize the malleus, incus, and stapes. The relationship of these bones to the middle ear cavity is determined and any masses identified. The inner ear is also assessed by CT and MRI. In the clinic Swimmer’s ear, often called otitis externa, is a painful condition resulting from an infection in the external acoustic meatus. It frequently occurs in swimmers. In the clinic Surfer’s ear, which is prevalent among individuals who surf or swim in cold water, results from the development of a “bony lump” in the external acoustic meatus. Growth of the lump eventually constricts the meatus and reduces hearing in the affected ear. In the clinic Although perforation of the tympanic membrane (eardrum) has many causes, trauma and infection are the most common. Ruptures of the tympanic membrane tend to heal spontaneously, but surgical intervention may be necessary if the rupture is large. | Anatomy_Gray. The middle ear is investigated by CT and MRI to visualize the malleus, incus, and stapes. The relationship of these bones to the middle ear cavity is determined and any masses identified. The inner ear is also assessed by CT and MRI. In the clinic Swimmer’s ear, often called otitis externa, is a painful condition resulting from an infection in the external acoustic meatus. It frequently occurs in swimmers. In the clinic Surfer’s ear, which is prevalent among individuals who surf or swim in cold water, results from the development of a “bony lump” in the external acoustic meatus. Growth of the lump eventually constricts the meatus and reduces hearing in the affected ear. In the clinic Although perforation of the tympanic membrane (eardrum) has many causes, trauma and infection are the most common. Ruptures of the tympanic membrane tend to heal spontaneously, but surgical intervention may be necessary if the rupture is large. |
Anatomy_Gray_2827 | Anatomy_Gray | Ruptures of the tympanic membrane tend to heal spontaneously, but surgical intervention may be necessary if the rupture is large. Occasionally, it may be necessary to enter the middle ear through the tympanic membrane. Because the chorda tympani runs in the upper one-third of the tympanic membrane, incisions are always below this level. The richer blood supply to the posterior aspect of the tympanic membrane determines the standard surgical approach in the posteroinferior aspect. Otitis media (infection of the middle ear) is common and can lead to perforation of the tympanic membrane. The infection can usually be treated with antibiotics. If the infection persists, the chronic inflammatory change may damage the ossicular chain and other structures within the middle ear to produce deafness. In the clinic | Anatomy_Gray. Ruptures of the tympanic membrane tend to heal spontaneously, but surgical intervention may be necessary if the rupture is large. Occasionally, it may be necessary to enter the middle ear through the tympanic membrane. Because the chorda tympani runs in the upper one-third of the tympanic membrane, incisions are always below this level. The richer blood supply to the posterior aspect of the tympanic membrane determines the standard surgical approach in the posteroinferior aspect. Otitis media (infection of the middle ear) is common and can lead to perforation of the tympanic membrane. The infection can usually be treated with antibiotics. If the infection persists, the chronic inflammatory change may damage the ossicular chain and other structures within the middle ear to produce deafness. In the clinic |
Anatomy_Gray_2828 | Anatomy_Gray | In the clinic Infection within the mastoid antrum and mastoid cells is usually secondary to infection in the middle ear. The mastoid cells provide an excellent culture medium for infection. Infection of the bone (osteomyelitis) may also develop, spreading into the middle cranial fossa. Drainage of the pus within the mastoid air cells is necessary and there are numerous approaches for doing this. When undertaking this type of surgery, it is extremely important that care is taken not to damage the mastoid wall of the middle ear to prevent injury to the facial nerve [VII]. Any breach of the inner table of the cranial vault may allow bacteria to enter the cranial cavity and meningitis will ensue. In the clinic A lingual nerve injury proximal to where the chorda tympani joins it in the infratemporal fossa will produce loss of general sensation from the anterior two-thirds of the tongue, oral mucosa, gingivae, the lower lip, and the chin. | Anatomy_Gray. In the clinic Infection within the mastoid antrum and mastoid cells is usually secondary to infection in the middle ear. The mastoid cells provide an excellent culture medium for infection. Infection of the bone (osteomyelitis) may also develop, spreading into the middle cranial fossa. Drainage of the pus within the mastoid air cells is necessary and there are numerous approaches for doing this. When undertaking this type of surgery, it is extremely important that care is taken not to damage the mastoid wall of the middle ear to prevent injury to the facial nerve [VII]. Any breach of the inner table of the cranial vault may allow bacteria to enter the cranial cavity and meningitis will ensue. In the clinic A lingual nerve injury proximal to where the chorda tympani joins it in the infratemporal fossa will produce loss of general sensation from the anterior two-thirds of the tongue, oral mucosa, gingivae, the lower lip, and the chin. |
Anatomy_Gray_2829 | Anatomy_Gray | If a lingual nerve lesion is distal to the site where it is joined by the chorda tympani, secretion from the salivary glands below the oral fissure and taste from the anterior two-thirds of the tongue will also be lost. In the clinic Anesthesia of the inferior alveolar nerve is widely practiced by most dentists. The inferior alveolar nerve is one of the largest branches of the mandibular nerve [V3], carries the sensory branches from the teeth and mandible, and receives sensory information from the skin over most of the mandible. The inferior alveolar nerve passes into the mandibular canal, courses through the body of the mandible, and eventually emerges through the mental foramen into the chin. | Anatomy_Gray. If a lingual nerve lesion is distal to the site where it is joined by the chorda tympani, secretion from the salivary glands below the oral fissure and taste from the anterior two-thirds of the tongue will also be lost. In the clinic Anesthesia of the inferior alveolar nerve is widely practiced by most dentists. The inferior alveolar nerve is one of the largest branches of the mandibular nerve [V3], carries the sensory branches from the teeth and mandible, and receives sensory information from the skin over most of the mandible. The inferior alveolar nerve passes into the mandibular canal, courses through the body of the mandible, and eventually emerges through the mental foramen into the chin. |
Anatomy_Gray_2830 | Anatomy_Gray | The inferior alveolar nerve passes into the mandibular canal, courses through the body of the mandible, and eventually emerges through the mental foramen into the chin. of the inferior alveolar nerve by local anesthetic. To anesthetize this nerve the needle is placed lateral to the anterior arch of the fauces (palatoglossal arch) in the oral cavity and is advanced along the medial border around the inferior third of the ramus of the mandible so that anesthetic can be deposited in this region. It is also possible to anesthetize the infra-orbital and buccal nerves, depending on where the anesthesia is needed. In the clinic | Anatomy_Gray. The inferior alveolar nerve passes into the mandibular canal, courses through the body of the mandible, and eventually emerges through the mental foramen into the chin. of the inferior alveolar nerve by local anesthetic. To anesthetize this nerve the needle is placed lateral to the anterior arch of the fauces (palatoglossal arch) in the oral cavity and is advanced along the medial border around the inferior third of the ramus of the mandible so that anesthetic can be deposited in this region. It is also possible to anesthetize the infra-orbital and buccal nerves, depending on where the anesthesia is needed. In the clinic |
Anatomy_Gray_2831 | Anatomy_Gray | It is also possible to anesthetize the infra-orbital and buccal nerves, depending on where the anesthesia is needed. In the clinic In most instances, access to peripheral veins of the arm and the leg will suffice for administering intravenous drugs and fluids and for obtaining blood for analysis; however, in certain circumstances it is necessary to place larger-bore catheters in the central veins, for example, for dialysis, parenteral nutrition, or the administration of drugs that have a tendency to produce phlebitis. | Anatomy_Gray. It is also possible to anesthetize the infra-orbital and buccal nerves, depending on where the anesthesia is needed. In the clinic In most instances, access to peripheral veins of the arm and the leg will suffice for administering intravenous drugs and fluids and for obtaining blood for analysis; however, in certain circumstances it is necessary to place larger-bore catheters in the central veins, for example, for dialysis, parenteral nutrition, or the administration of drugs that have a tendency to produce phlebitis. |
Anatomy_Gray_2832 | Anatomy_Gray | “Blind puncture” of the subclavian and jugular veins to obtain central venous access used to be standard practice. However, subclavian vein puncture is not without complications. As the subclavian vein passes inferiorly, posterior to the clavicle, it passes over the apex of the lung. Any misplacement of a needle into or through this structure may puncture the apical pleura, producing a pneumothorax. Inadvertent arterial puncture and vein laceration may also produce a hemopneumothorax. A puncture of the internal jugular vein (Fig. 8.165) carries fewer risks, but local hematoma and damage to the carotid artery are again important complications. Current practice is to identify major vessels using ultrasound and to obtain central venous access under direct vision to avoid any significant complication. In the clinic | Anatomy_Gray. “Blind puncture” of the subclavian and jugular veins to obtain central venous access used to be standard practice. However, subclavian vein puncture is not without complications. As the subclavian vein passes inferiorly, posterior to the clavicle, it passes over the apex of the lung. Any misplacement of a needle into or through this structure may puncture the apical pleura, producing a pneumothorax. Inadvertent arterial puncture and vein laceration may also produce a hemopneumothorax. A puncture of the internal jugular vein (Fig. 8.165) carries fewer risks, but local hematoma and damage to the carotid artery are again important complications. Current practice is to identify major vessels using ultrasound and to obtain central venous access under direct vision to avoid any significant complication. In the clinic |
Anatomy_Gray_2833 | Anatomy_Gray | Current practice is to identify major vessels using ultrasound and to obtain central venous access under direct vision to avoid any significant complication. In the clinic The jugular venous pulse is an important clinical sign that enables the physician to assess the venous pressure and waveform and is a reflection of the functioning of the right side of the heart. In the clinic The thyroid gland develops from a small region of tissue near the base of the tongue. This tissue descends as the thyroglossal duct from the foramen cecum in the posterior aspect of the tongue to pass adjacent to the anterior aspect of the middle of the hyoid bone. The thyroid tissue continues to migrate inferiorly and eventually comes to rest at the anterior aspect of the trachea in the root of the neck. | Anatomy_Gray. Current practice is to identify major vessels using ultrasound and to obtain central venous access under direct vision to avoid any significant complication. In the clinic The jugular venous pulse is an important clinical sign that enables the physician to assess the venous pressure and waveform and is a reflection of the functioning of the right side of the heart. In the clinic The thyroid gland develops from a small region of tissue near the base of the tongue. This tissue descends as the thyroglossal duct from the foramen cecum in the posterior aspect of the tongue to pass adjacent to the anterior aspect of the middle of the hyoid bone. The thyroid tissue continues to migrate inferiorly and eventually comes to rest at the anterior aspect of the trachea in the root of the neck. |
Anatomy_Gray_2834 | Anatomy_Gray | Consequently, the migration of thyroid tissue may be arrested anywhere along the embryological descent of the gland. Ectopic thyroid tissue is relatively rare. More frequently seen is the cystic change that arises from the thyroglossal duct. The usual symptom of a thyroglossal duct cyst is a midline mass. Ultrasound easily demonstrates its nature and position, and treatment is by surgical excision. The whole of the duct as well as a small part of the anterior aspect of the hyoid bone must be excised to prevent recurrence. In the clinic A thyroidectomy is a common surgical procedure. In most cases it involves excision of part or most of the thyroid gland. This surgical procedure is usually carried out for benign diseases, such as multinodular goiter and thyroid cancer. | Anatomy_Gray. Consequently, the migration of thyroid tissue may be arrested anywhere along the embryological descent of the gland. Ectopic thyroid tissue is relatively rare. More frequently seen is the cystic change that arises from the thyroglossal duct. The usual symptom of a thyroglossal duct cyst is a midline mass. Ultrasound easily demonstrates its nature and position, and treatment is by surgical excision. The whole of the duct as well as a small part of the anterior aspect of the hyoid bone must be excised to prevent recurrence. In the clinic A thyroidectomy is a common surgical procedure. In most cases it involves excision of part or most of the thyroid gland. This surgical procedure is usually carried out for benign diseases, such as multinodular goiter and thyroid cancer. |
Anatomy_Gray_2835 | Anatomy_Gray | Given the location of the thyroid gland, there is a possibility of damaging other structures when carrying out a thyroidectomy, namely the parathyroid glands and the recurrent laryngeal nerve (Fig. 8.181). Assessment of the vocal folds is necessary before and after thyroid surgery because the recurrent laryngeal nerves are closely related to ligaments that bind the gland to the larynx and can be easily traumatized during surgical procedures. In the clinic Thyroid gland pathology is extremely complex. In essence, thyroid gland pathology should be assessed from two points of view. First, the thyroid gland may be diffusely or focally enlarged, for which there are numerous causes. Second, the thyroid gland may undersecrete or oversecrete the hormone thyroxine. | Anatomy_Gray. Given the location of the thyroid gland, there is a possibility of damaging other structures when carrying out a thyroidectomy, namely the parathyroid glands and the recurrent laryngeal nerve (Fig. 8.181). Assessment of the vocal folds is necessary before and after thyroid surgery because the recurrent laryngeal nerves are closely related to ligaments that bind the gland to the larynx and can be easily traumatized during surgical procedures. In the clinic Thyroid gland pathology is extremely complex. In essence, thyroid gland pathology should be assessed from two points of view. First, the thyroid gland may be diffusely or focally enlarged, for which there are numerous causes. Second, the thyroid gland may undersecrete or oversecrete the hormone thyroxine. |
Anatomy_Gray_2836 | Anatomy_Gray | One of the commonest disorders of the thyroid gland is a multinodular goiter, which is a diffuse irregular enlargement of the thyroid gland with areas of thyroid hypertrophy and colloid cyst formation. Most patients are euthyroid (i.e., have normal serum thyroxine levels). The typical symptom is a diffuse mass in the neck, which may be managed medically or may need surgical excision if the mass is large enough to affect the patient’s life or cause respiratory problems. Isolated nodules in the thyroid gland may be a dominant nodule in a multinodular gland or possibly an isolated tumor of the thyroid gland. Isolated tumors may or may not secrete thyroxine depending on their cellular morphology. Treatment is usually by excision. | Anatomy_Gray. One of the commonest disorders of the thyroid gland is a multinodular goiter, which is a diffuse irregular enlargement of the thyroid gland with areas of thyroid hypertrophy and colloid cyst formation. Most patients are euthyroid (i.e., have normal serum thyroxine levels). The typical symptom is a diffuse mass in the neck, which may be managed medically or may need surgical excision if the mass is large enough to affect the patient’s life or cause respiratory problems. Isolated nodules in the thyroid gland may be a dominant nodule in a multinodular gland or possibly an isolated tumor of the thyroid gland. Isolated tumors may or may not secrete thyroxine depending on their cellular morphology. Treatment is usually by excision. |
Anatomy_Gray_2837 | Anatomy_Gray | Immunological diseases may affect the thyroid gland and may overstimulate it to produce excessive thyroxine. These diseases may be associated with other extrathyroid manifestations, which include exophthalmos, pretibial myxedema, and nail changes. Other causes of diffuse thyroid stimulation include viral thyroiditis. Some diseases may cause atrophy of the thyroid gland, leading to undersecretion of thyroxine (myxedema). In the clinic The parathyroid glands develop from the third and fourth pharyngeal pouches and translocate to their more adult locations during development. The position of the glands can be highly variable, sometimes being situated high in the neck or in the thorax. Tumors develop in any of these locations (Fig. 8.182). In the clinic | Anatomy_Gray. Immunological diseases may affect the thyroid gland and may overstimulate it to produce excessive thyroxine. These diseases may be associated with other extrathyroid manifestations, which include exophthalmos, pretibial myxedema, and nail changes. Other causes of diffuse thyroid stimulation include viral thyroiditis. Some diseases may cause atrophy of the thyroid gland, leading to undersecretion of thyroxine (myxedema). In the clinic The parathyroid glands develop from the third and fourth pharyngeal pouches and translocate to their more adult locations during development. The position of the glands can be highly variable, sometimes being situated high in the neck or in the thorax. Tumors develop in any of these locations (Fig. 8.182). In the clinic |
Anatomy_Gray_2838 | Anatomy_Gray | In the clinic Damage to either the right or left recurrent laryngeal nerve may lead initially to a hoarse voice and finally to an inability to speak. Recurrent laryngeal nerve palsy can occur from disruption of the nerves anywhere along their course. Furthermore, interruption of the vagus nerves before the division of the recurrent laryngeal nerves can also produce vocal symptoms. Lung cancer in the apex of the right lung can affect the right recurrent laryngeal nerve, whereas cancers that infiltrate into the area between the pulmonary artery and aorta, an area known clinically as the “aortopulmonary window,” can affect the left recurrent laryngeal nerve. Thyroid surgery also can traumatize the recurrent laryngeal nerves. In the clinic Clinical lymphatic drainage of the head and neck | Anatomy_Gray. In the clinic Damage to either the right or left recurrent laryngeal nerve may lead initially to a hoarse voice and finally to an inability to speak. Recurrent laryngeal nerve palsy can occur from disruption of the nerves anywhere along their course. Furthermore, interruption of the vagus nerves before the division of the recurrent laryngeal nerves can also produce vocal symptoms. Lung cancer in the apex of the right lung can affect the right recurrent laryngeal nerve, whereas cancers that infiltrate into the area between the pulmonary artery and aorta, an area known clinically as the “aortopulmonary window,” can affect the left recurrent laryngeal nerve. Thyroid surgery also can traumatize the recurrent laryngeal nerves. In the clinic Clinical lymphatic drainage of the head and neck |
Anatomy_Gray_2839 | Anatomy_Gray | In the clinic Clinical lymphatic drainage of the head and neck Enlargement of the neck lymph nodes (cervical lymphadenopathy) is a common manifestation of disease processes that occur in the head and neck. It is also a common manifestation of diffuse diseases of the body, which include lymphoma, sarcoidosis, and certain types of viral infection such as glandular fever and human immunodeficiency virus (HIV) infection. Evaluation of cervical lymph nodes is extremely important in determining the nature and etiology of the primary disease process that has produced nodal enlargement. Clinical evaluation includes a general health assessment, particularly relating to symptoms from the head and neck. Examination of the nodes themselves often gives the clinician a clue as to the nature of the pathological process. Soft, tender, and inflamed lymph nodes suggest an acute inflammatory process, which is most likely to be infective. | Anatomy_Gray. In the clinic Clinical lymphatic drainage of the head and neck Enlargement of the neck lymph nodes (cervical lymphadenopathy) is a common manifestation of disease processes that occur in the head and neck. It is also a common manifestation of diffuse diseases of the body, which include lymphoma, sarcoidosis, and certain types of viral infection such as glandular fever and human immunodeficiency virus (HIV) infection. Evaluation of cervical lymph nodes is extremely important in determining the nature and etiology of the primary disease process that has produced nodal enlargement. Clinical evaluation includes a general health assessment, particularly relating to symptoms from the head and neck. Examination of the nodes themselves often gives the clinician a clue as to the nature of the pathological process. Soft, tender, and inflamed lymph nodes suggest an acute inflammatory process, which is most likely to be infective. |
Anatomy_Gray_2840 | Anatomy_Gray | Soft, tender, and inflamed lymph nodes suggest an acute inflammatory process, which is most likely to be infective. Firm multinodular large-volume rubbery nodes often suggest a diagnosis of lymphoma. Examination should also include careful assessment of other nodal regions, including the supraclavicular fossae, the axillae, the retroperitoneum, and the inguinal regions. Further examination may include digestive tract endoscopy, chest radiography, and body CT scanning. Most cervical lymph nodes are easily palpable and suitable for biopsy to establish a tissue diagnosis. Biopsy can be performed using ultrasound for guidance and good samples of lymph nodes may be obtained. | Anatomy_Gray. Soft, tender, and inflamed lymph nodes suggest an acute inflammatory process, which is most likely to be infective. Firm multinodular large-volume rubbery nodes often suggest a diagnosis of lymphoma. Examination should also include careful assessment of other nodal regions, including the supraclavicular fossae, the axillae, the retroperitoneum, and the inguinal regions. Further examination may include digestive tract endoscopy, chest radiography, and body CT scanning. Most cervical lymph nodes are easily palpable and suitable for biopsy to establish a tissue diagnosis. Biopsy can be performed using ultrasound for guidance and good samples of lymph nodes may be obtained. |
Anatomy_Gray_2841 | Anatomy_Gray | The lymphatic drainage of the neck is somewhat complex, clinically. A relatively simple “level” system of nodal enlargement has been designed that is extremely helpful in evaluating lymph node spread of primary head and neck tumors. Once the number of levels of nodes are determined, and the size of the lymph nodes, the best mode of treatment can be instituted. This may include surgery, radiotherapy, and chemotherapy. The lymph node level also enables a prognosis to be made. The levels are as follows (Fig. 8.199): Level I—from the midline of the submental triangle up to the level of the submandibular gland. Level II—from the skull base to the level of the hyoid bone anteriorly from the posterior border of the sternocleidomastoid muscle. Level III—the inferior aspect of the hyoid bone to the bottom cricoid arch and anterior to the posterior border of the sternocleidomastoid up to the midline. | Anatomy_Gray. The lymphatic drainage of the neck is somewhat complex, clinically. A relatively simple “level” system of nodal enlargement has been designed that is extremely helpful in evaluating lymph node spread of primary head and neck tumors. Once the number of levels of nodes are determined, and the size of the lymph nodes, the best mode of treatment can be instituted. This may include surgery, radiotherapy, and chemotherapy. The lymph node level also enables a prognosis to be made. The levels are as follows (Fig. 8.199): Level I—from the midline of the submental triangle up to the level of the submandibular gland. Level II—from the skull base to the level of the hyoid bone anteriorly from the posterior border of the sternocleidomastoid muscle. Level III—the inferior aspect of the hyoid bone to the bottom cricoid arch and anterior to the posterior border of the sternocleidomastoid up to the midline. |
Anatomy_Gray_2842 | Anatomy_Gray | Level III—the inferior aspect of the hyoid bone to the bottom cricoid arch and anterior to the posterior border of the sternocleidomastoid up to the midline. Level IV—from the inferior aspect of the cricoid to the top of the manubrium of the sternum and anterior to the posterior border of the sternocleidomastoid muscle. Level V—posterior to the sternocleidomastoid muscle and anterior to the trapezius muscle above the level of the clavicle. Level VI—below the hyoid bone and above the jugular (sternal) notch in the midline. Level VII—below the level of the jugular (sternal) notch. In the clinic | Anatomy_Gray. Level III—the inferior aspect of the hyoid bone to the bottom cricoid arch and anterior to the posterior border of the sternocleidomastoid up to the midline. Level IV—from the inferior aspect of the cricoid to the top of the manubrium of the sternum and anterior to the posterior border of the sternocleidomastoid muscle. Level V—posterior to the sternocleidomastoid muscle and anterior to the trapezius muscle above the level of the clavicle. Level VI—below the hyoid bone and above the jugular (sternal) notch in the midline. Level VII—below the level of the jugular (sternal) notch. In the clinic |
Anatomy_Gray_2843 | Anatomy_Gray | Level VI—below the hyoid bone and above the jugular (sternal) notch in the midline. Level VII—below the level of the jugular (sternal) notch. In the clinic In emergency situations, when the airway is blocked above the level of the vocal folds, the median cricothyroid ligament can be perforated and a small tube inserted through the incision to establish an airway. Except for small vessels and the occasional presence of a pyramidal lobe of the thyroid gland, normally there are few structures between the median cricothyroid ligament and the skin. In the clinic A tracheostomy is a surgical procedure in which a hole is made in the trachea and a tube is inserted to enable ventilation. A tracheostomy is typically performed when there is obstruction to the larynx as a result of inhalation of a foreign body, severe edema secondary to anaphylactic reaction, or severe head and neck trauma. | Anatomy_Gray. Level VI—below the hyoid bone and above the jugular (sternal) notch in the midline. Level VII—below the level of the jugular (sternal) notch. In the clinic In emergency situations, when the airway is blocked above the level of the vocal folds, the median cricothyroid ligament can be perforated and a small tube inserted through the incision to establish an airway. Except for small vessels and the occasional presence of a pyramidal lobe of the thyroid gland, normally there are few structures between the median cricothyroid ligament and the skin. In the clinic A tracheostomy is a surgical procedure in which a hole is made in the trachea and a tube is inserted to enable ventilation. A tracheostomy is typically performed when there is obstruction to the larynx as a result of inhalation of a foreign body, severe edema secondary to anaphylactic reaction, or severe head and neck trauma. |
Anatomy_Gray_2844 | Anatomy_Gray | The typical situation in which a tracheostomy is performed is in the calm atmosphere of an operating theater. A small transverse incision is placed in the lower third of the neck anteriorly. The strap muscles are deviated laterally and the trachea can be easily visualized. Occasionally it is necessary to divide the isthmus of the thyroid gland. An incision is made in the second and third tracheal rings and a small tracheostomy tube inserted. After the tracheostomy has been in situ for the required length of time, it is simply removed. The hole through which it was inserted almost inevitably closes without any intervention. Patients with long-term tracheostomies are unable to vocalize because no air is passing through the vocal cords. In the clinic | Anatomy_Gray. The typical situation in which a tracheostomy is performed is in the calm atmosphere of an operating theater. A small transverse incision is placed in the lower third of the neck anteriorly. The strap muscles are deviated laterally and the trachea can be easily visualized. Occasionally it is necessary to divide the isthmus of the thyroid gland. An incision is made in the second and third tracheal rings and a small tracheostomy tube inserted. After the tracheostomy has been in situ for the required length of time, it is simply removed. The hole through which it was inserted almost inevitably closes without any intervention. Patients with long-term tracheostomies are unable to vocalize because no air is passing through the vocal cords. In the clinic |
Anatomy_Gray_2845 | Anatomy_Gray | Patients with long-term tracheostomies are unable to vocalize because no air is passing through the vocal cords. In the clinic Laryngoscopy is a medical procedure that is used to inspect the larynx. The functions of laryngoscopy include the evaluation of patients with difficulty swallowing, assessment of the vocal cords, and assessment of the larynx for tumors, masses, and weak voice. | Anatomy_Gray. Patients with long-term tracheostomies are unable to vocalize because no air is passing through the vocal cords. In the clinic Laryngoscopy is a medical procedure that is used to inspect the larynx. The functions of laryngoscopy include the evaluation of patients with difficulty swallowing, assessment of the vocal cords, and assessment of the larynx for tumors, masses, and weak voice. |
Anatomy_Gray_2846 | Anatomy_Gray | The larynx is typically visualized using two methods. Indirect laryngoscopy involves passage of a small rod-mounted mirror (not dissimilar to a dental mirror) into the oropharynx permitting indirect visualization of the larynx. Direct laryngoscopy can be performed using a device with a curved metal tip that holds the tongue and epiglottis forward, allowing direct inspection of the larynx. This procedure can be performed only in the unconscious patient or in a patient in whom the gag reflex is not intact. Other methods of inspection include the passage of fiberoptic endoscopes through either the oral cavity or nasal cavity. In the clinic The nasal septum is typically situated in the midline; however, septal deviation to one side or the other is not uncommon, and in many cases is secondary to direct trauma. Extreme septal deviation can produce nasal occlusion. The deviation can be corrected surgically. In the clinic | Anatomy_Gray. The larynx is typically visualized using two methods. Indirect laryngoscopy involves passage of a small rod-mounted mirror (not dissimilar to a dental mirror) into the oropharynx permitting indirect visualization of the larynx. Direct laryngoscopy can be performed using a device with a curved metal tip that holds the tongue and epiglottis forward, allowing direct inspection of the larynx. This procedure can be performed only in the unconscious patient or in a patient in whom the gag reflex is not intact. Other methods of inspection include the passage of fiberoptic endoscopes through either the oral cavity or nasal cavity. In the clinic The nasal septum is typically situated in the midline; however, septal deviation to one side or the other is not uncommon, and in many cases is secondary to direct trauma. Extreme septal deviation can produce nasal occlusion. The deviation can be corrected surgically. In the clinic |
Anatomy_Gray_2847 | Anatomy_Gray | In the clinic Most cancers of the oral cavity, oropharynx, nasopharynx, larynx, sinuses, and salivary glands arise from the epithelial cells that line them, resulting in squamous cell carcinoma. The majority of these are related to cell damage caused by smoking and alcohol use. Certain viruses are also related to cancers in the head and neck, including human papillomavirus (HPV) and Epstein-Barr virus (EBV). A 50-year-old overweight woman came to the doctor complaining of hoarseness of voice and noisy breathing. She was also concerned at the increase in size of her neck. On examination she had a slow pulse rate (45 beats per minute). She also had an irregular knobby mass in the anterior aspect of the lower neck, which deviated the trachea to the right. A clinical diagnosis of a multinodular goiter and hypothyroidism was made. | Anatomy_Gray. In the clinic Most cancers of the oral cavity, oropharynx, nasopharynx, larynx, sinuses, and salivary glands arise from the epithelial cells that line them, resulting in squamous cell carcinoma. The majority of these are related to cell damage caused by smoking and alcohol use. Certain viruses are also related to cancers in the head and neck, including human papillomavirus (HPV) and Epstein-Barr virus (EBV). A 50-year-old overweight woman came to the doctor complaining of hoarseness of voice and noisy breathing. She was also concerned at the increase in size of her neck. On examination she had a slow pulse rate (45 beats per minute). She also had an irregular knobby mass in the anterior aspect of the lower neck, which deviated the trachea to the right. A clinical diagnosis of a multinodular goiter and hypothyroidism was made. |
Anatomy_Gray_2848 | Anatomy_Gray | A clinical diagnosis of a multinodular goiter and hypothyroidism was made. Enlargement of the thyroid gland is due to increased secretion of thyroid-stimulating hormone, which is usually secondary to diminished output of thyroid hormones. The thyroid undergoes periods of activity and regression, which can lead to the formation of nodules, some of which are solid and some of which are partially cystic (colloid cysts). This nodule formation is compounded by areas of fibrosis within the gland. Other causes of multinodular goiter include iodine deficiency and in certain circumstances, drugs that interfere with the metabolism and production of thyroxine. The typical symptom of a goiter is a painless swelling of the thyroid gland. It may be smooth or nodular, and occasionally it may extend into the superior mediastinum as a retrosternal goiter. The trachea was deviated. | Anatomy_Gray. A clinical diagnosis of a multinodular goiter and hypothyroidism was made. Enlargement of the thyroid gland is due to increased secretion of thyroid-stimulating hormone, which is usually secondary to diminished output of thyroid hormones. The thyroid undergoes periods of activity and regression, which can lead to the formation of nodules, some of which are solid and some of which are partially cystic (colloid cysts). This nodule formation is compounded by areas of fibrosis within the gland. Other causes of multinodular goiter include iodine deficiency and in certain circumstances, drugs that interfere with the metabolism and production of thyroxine. The typical symptom of a goiter is a painless swelling of the thyroid gland. It may be smooth or nodular, and occasionally it may extend into the superior mediastinum as a retrosternal goiter. The trachea was deviated. |
Anatomy_Gray_2849 | Anatomy_Gray | The trachea was deviated. The enlargement of the thyroid gland due to a multinodular goiter may not be symmetrical. In this case there was significant asymmetrical enlargement of the left lobe of the thyroid deviating the trachea to the right. The patient had a hoarse voice and noisy breathing. If the thyroid gland enlargement is significant it can compress the trachea, narrowing it to such an extent that a “crowing sound” is heard during inspiration (stridor). Other possible causes for hoarseness include paralysis of the vocal cord due to compression of the left recurrent laryngeal nerve from the goiter. Of concern is the possibility of malignant change within the goiter directly invading the recurrent laryngeal nerve. Fortunately, malignant change is rare within the thyroid gland. | Anatomy_Gray. The trachea was deviated. The enlargement of the thyroid gland due to a multinodular goiter may not be symmetrical. In this case there was significant asymmetrical enlargement of the left lobe of the thyroid deviating the trachea to the right. The patient had a hoarse voice and noisy breathing. If the thyroid gland enlargement is significant it can compress the trachea, narrowing it to such an extent that a “crowing sound” is heard during inspiration (stridor). Other possible causes for hoarseness include paralysis of the vocal cord due to compression of the left recurrent laryngeal nerve from the goiter. Of concern is the possibility of malignant change within the goiter directly invading the recurrent laryngeal nerve. Fortunately, malignant change is rare within the thyroid gland. |
Anatomy_Gray_2850 | Anatomy_Gray | When patients have a relatively low production of thyroxine such that the basal metabolic rate is reduced they become more susceptible to infection, including throat and upper respiratory tract infections. On examination the thyroid gland moved during swallowing. Characteristically, an enlarged thyroid gland is evident as a neck mass arising on one or both sides of the trachea. The enlarged thyroid gland moves on swallowing because it is attached to the larynx by the pretracheal fascia. The patient was hypothyroid. Hypothyroidism refers to the clinical and biochemical state in which the thyroid gland is underactive (hyperthyroidism refers to an overactive thyroid gland). Some patients have thyroid masses and no clinical or biochemical abnormalities—these patients are euthyroid. | Anatomy_Gray. When patients have a relatively low production of thyroxine such that the basal metabolic rate is reduced they become more susceptible to infection, including throat and upper respiratory tract infections. On examination the thyroid gland moved during swallowing. Characteristically, an enlarged thyroid gland is evident as a neck mass arising on one or both sides of the trachea. The enlarged thyroid gland moves on swallowing because it is attached to the larynx by the pretracheal fascia. The patient was hypothyroid. Hypothyroidism refers to the clinical and biochemical state in which the thyroid gland is underactive (hyperthyroidism refers to an overactive thyroid gland). Some patients have thyroid masses and no clinical or biochemical abnormalities—these patients are euthyroid. |
Anatomy_Gray_2851 | Anatomy_Gray | The hormone thyroxine controls the basal metabolic rate; therefore, low levels of thyroxine affect the resting pulse rate and may produce other changes, including weight gain, and in some cases depression. The patient was insistent upon surgery. After discussion about the risks and complications, a subtotal thyroidectomy was performed. After the procedure the patient complained of tingling in her hands and feet and around her mouth, and carpopedal spasm. These symptoms are typical of tetany and are caused by low serum calcium levels. | Anatomy_Gray. The hormone thyroxine controls the basal metabolic rate; therefore, low levels of thyroxine affect the resting pulse rate and may produce other changes, including weight gain, and in some cases depression. The patient was insistent upon surgery. After discussion about the risks and complications, a subtotal thyroidectomy was performed. After the procedure the patient complained of tingling in her hands and feet and around her mouth, and carpopedal spasm. These symptoms are typical of tetany and are caused by low serum calcium levels. |
Anatomy_Gray_2852 | Anatomy_Gray | The etiology of the low serum calcium level was trauma and bruising of the four parathyroid glands left in situ after the operation. Undoubtedly the trauma of removal of such a large thyroid gland produced a change within the parathyroid gland, which failed to function appropriately. The secretion of parathyroid hormone rapidly decreased over the next 24 hours, resulting in increased excitability of peripheral nerves, manifest by carpopedal spasm and orofacial tingling. Muscle spasms can also be elicited by tapping the facial nerve [VII] as it emerges from the parotid gland to produce twitching of the facial muscles (Chvostek’s sign). The patient recovered from these symptoms due to a low calcium level over the next 24 hours. At her return to the clinic the patient was placed on supplementary oral thyroxine, which is necessary after removal of the thyroid gland. The patient also complained of a hoarse voice. | Anatomy_Gray. The etiology of the low serum calcium level was trauma and bruising of the four parathyroid glands left in situ after the operation. Undoubtedly the trauma of removal of such a large thyroid gland produced a change within the parathyroid gland, which failed to function appropriately. The secretion of parathyroid hormone rapidly decreased over the next 24 hours, resulting in increased excitability of peripheral nerves, manifest by carpopedal spasm and orofacial tingling. Muscle spasms can also be elicited by tapping the facial nerve [VII] as it emerges from the parotid gland to produce twitching of the facial muscles (Chvostek’s sign). The patient recovered from these symptoms due to a low calcium level over the next 24 hours. At her return to the clinic the patient was placed on supplementary oral thyroxine, which is necessary after removal of the thyroid gland. The patient also complained of a hoarse voice. |
Anatomy_Gray_2853 | Anatomy_Gray | At her return to the clinic the patient was placed on supplementary oral thyroxine, which is necessary after removal of the thyroid gland. The patient also complained of a hoarse voice. The etiology of her hoarse voice was damage to the recurrent laryngeal nerve. The recurrent laryngeal nerve lies close to the thyroid gland. It may be damaged in difficult surgical procedures, and this may produce unilateral spasm of the ipsilateral vocal cord to produce a hoarse voice. Since the thyroidectomy and institution of thyroxine treatment, the patient has lost weight and has no further complaints. | Anatomy_Gray. At her return to the clinic the patient was placed on supplementary oral thyroxine, which is necessary after removal of the thyroid gland. The patient also complained of a hoarse voice. The etiology of her hoarse voice was damage to the recurrent laryngeal nerve. The recurrent laryngeal nerve lies close to the thyroid gland. It may be damaged in difficult surgical procedures, and this may produce unilateral spasm of the ipsilateral vocal cord to produce a hoarse voice. Since the thyroidectomy and institution of thyroxine treatment, the patient has lost weight and has no further complaints. |
Anatomy_Gray_2854 | Anatomy_Gray | Since the thyroidectomy and institution of thyroxine treatment, the patient has lost weight and has no further complaints. A 33-year-old man was playing cricket for his local Sunday team. As the new bowler pitched the ball short, it bounced higher than he anticipated and hit him on the side of his head. He immediately fell to the ground unconscious, but after about 30 seconds he was helped to his feet and felt otherwise well. It was noted he had some bruising around his temple. He decided not to continue playing and went to watch the match from the side. Over the next hour he became extremely sleepy and was eventually unrousable. He was rushed to hospital. When he was admitted to hospital, the patient’s breathing was shallow and irregular and it was necessary to intubate him. A skull radiograph demonstrated a fracture in the region of the pterion. No other abnormality was demonstrated other than minor soft tissue bruising over the left temporal fossa. A CT scan was performed. | Anatomy_Gray. Since the thyroidectomy and institution of thyroxine treatment, the patient has lost weight and has no further complaints. A 33-year-old man was playing cricket for his local Sunday team. As the new bowler pitched the ball short, it bounced higher than he anticipated and hit him on the side of his head. He immediately fell to the ground unconscious, but after about 30 seconds he was helped to his feet and felt otherwise well. It was noted he had some bruising around his temple. He decided not to continue playing and went to watch the match from the side. Over the next hour he became extremely sleepy and was eventually unrousable. He was rushed to hospital. When he was admitted to hospital, the patient’s breathing was shallow and irregular and it was necessary to intubate him. A skull radiograph demonstrated a fracture in the region of the pterion. No other abnormality was demonstrated other than minor soft tissue bruising over the left temporal fossa. A CT scan was performed. |
Anatomy_Gray_2855 | Anatomy_Gray | A CT scan was performed. The CT scan demonstrated a lentiform area of high density within the left cranial fossa. A diagnosis of extradural hemorrhage was made. Fractures in the region of the pterion are extremely dangerous. A division of the middle meningeal artery passes deep to this structure and is subject to laceration and disruption, especially in conjunction with a skull injury in this region. In this case the middle meningeal artery was torn and started to bleed, producing a large extradural clot. The patient’s blood pressure began to increase. | Anatomy_Gray. A CT scan was performed. The CT scan demonstrated a lentiform area of high density within the left cranial fossa. A diagnosis of extradural hemorrhage was made. Fractures in the region of the pterion are extremely dangerous. A division of the middle meningeal artery passes deep to this structure and is subject to laceration and disruption, especially in conjunction with a skull injury in this region. In this case the middle meningeal artery was torn and started to bleed, producing a large extradural clot. The patient’s blood pressure began to increase. |
Anatomy_Gray_2856 | Anatomy_Gray | The patient’s blood pressure began to increase. Within the skull there is a fixed volume and clearly what goes in must come out (e.g., blood, cerebrospinal fluid). If there is a space-occupying lesion, such as an extradural hematoma, there is no space into which it can decompress. As the lesion expands, the brain becomes compressed and the intracranial pressure increases. This pressure compresses vessels, so lowering the cerebral perfusion pressure. To combat this the homeostatic mechanisms of the body increase the blood pressure to overcome the increase in intracerebral pressure. Unfortunately, the increase in intracranial pressure is compounded by the cerebral edema that occurs at and after the initial insult. An urgent surgical procedure was performed. | Anatomy_Gray. The patient’s blood pressure began to increase. Within the skull there is a fixed volume and clearly what goes in must come out (e.g., blood, cerebrospinal fluid). If there is a space-occupying lesion, such as an extradural hematoma, there is no space into which it can decompress. As the lesion expands, the brain becomes compressed and the intracranial pressure increases. This pressure compresses vessels, so lowering the cerebral perfusion pressure. To combat this the homeostatic mechanisms of the body increase the blood pressure to overcome the increase in intracerebral pressure. Unfortunately, the increase in intracranial pressure is compounded by the cerebral edema that occurs at and after the initial insult. An urgent surgical procedure was performed. |
Anatomy_Gray_2857 | Anatomy_Gray | An urgent surgical procedure was performed. Burr holes were placed around the region of the hematoma and it was evacuated. The small branch of the middle meningeal artery was ligated and the patient spent a few days in the intensive care unit. Fortunately the patient made an uneventful recovery. A 35-year-old man was involved in a fight and sustained a punch to the right orbit. He came to the emergency department with double vision. The double vision was only in one plane. Examination of the orbits revealed that when the patient was asked to look upward the right eye was unable to move superiorly when adducted. There was some limitation in general eye movement. Assessment of the lateral rectus muscle (abducent nerve [VI]), superior oblique muscle (trochlear nerve [IV]), and the rest of the eye muscles (oculomotor nerve [III]) was otherwise unremarkable. The patient underwent a CT scan. | Anatomy_Gray. An urgent surgical procedure was performed. Burr holes were placed around the region of the hematoma and it was evacuated. The small branch of the middle meningeal artery was ligated and the patient spent a few days in the intensive care unit. Fortunately the patient made an uneventful recovery. A 35-year-old man was involved in a fight and sustained a punch to the right orbit. He came to the emergency department with double vision. The double vision was only in one plane. Examination of the orbits revealed that when the patient was asked to look upward the right eye was unable to move superiorly when adducted. There was some limitation in general eye movement. Assessment of the lateral rectus muscle (abducent nerve [VI]), superior oblique muscle (trochlear nerve [IV]), and the rest of the eye muscles (oculomotor nerve [III]) was otherwise unremarkable. The patient underwent a CT scan. |
Anatomy_Gray_2858 | Anatomy_Gray | The patient underwent a CT scan. A CT scan of the facial bones demonstrated a fracture through the floor of the orbit (Fig. 8.293). A careful review of this CT scan demonstrated that the inferior oblique muscle had been pulled inferiorly with the fragment of bone in the fracture. This produced a tethering effect, so when the patient was asked to gaze in the upward direction, the left eye was able to do so but the right eye was unable to because of the tethered inferior oblique muscle. The patient underwent surgical exploration to elevate the small bony fragment and return the inferior oblique to its appropriate position. On follow-up the patient had no complications. | Anatomy_Gray. The patient underwent a CT scan. A CT scan of the facial bones demonstrated a fracture through the floor of the orbit (Fig. 8.293). A careful review of this CT scan demonstrated that the inferior oblique muscle had been pulled inferiorly with the fragment of bone in the fracture. This produced a tethering effect, so when the patient was asked to gaze in the upward direction, the left eye was able to do so but the right eye was unable to because of the tethered inferior oblique muscle. The patient underwent surgical exploration to elevate the small bony fragment and return the inferior oblique to its appropriate position. On follow-up the patient had no complications. |
Anatomy_Gray_2859 | Anatomy_Gray | The patient underwent surgical exploration to elevate the small bony fragment and return the inferior oblique to its appropriate position. On follow-up the patient had no complications. A 25-year-old man complained of significant swelling in front of his right ear before and around mealtimes. This swelling was associated with considerable pain, which was provoked by the ingestion of lemon sweets. On examination he had tenderness around the right parotid region and a hard nodule was demonstrated in the buccal mucosa adjacent to the right upper molar teeth. A diagnosis of parotid duct calculus was made. | Anatomy_Gray. The patient underwent surgical exploration to elevate the small bony fragment and return the inferior oblique to its appropriate position. On follow-up the patient had no complications. A 25-year-old man complained of significant swelling in front of his right ear before and around mealtimes. This swelling was associated with considerable pain, which was provoked by the ingestion of lemon sweets. On examination he had tenderness around the right parotid region and a hard nodule was demonstrated in the buccal mucosa adjacent to the right upper molar teeth. A diagnosis of parotid duct calculus was made. |
Anatomy_Gray_2860 | Anatomy_Gray | A diagnosis of parotid duct calculus was made. The formation of stones in the salivary glands is not uncommon, but it is more likely in the submandibular gland than in the parotid gland because the saliva is more mucinous and the duct has a long upward course from the floor of the mouth. Nevertheless, stones do form in the parotid gland and the parotid ducts. Notably, most parotid duct calculi and submandibular duct calculi occur in mouths with excellent dental hygiene and mucosa. An ultrasound scan was performed. An initial ultrasound scan demonstrated a stone in the distal end of the right parotid duct with evidence of ductal dilation (eFig. 8.294). Assessment of the gland also demonstrated dilated ducts within the gland and evidence of intraparotid lymphadenopathy. The patient was treated with antibiotics. | Anatomy_Gray. A diagnosis of parotid duct calculus was made. The formation of stones in the salivary glands is not uncommon, but it is more likely in the submandibular gland than in the parotid gland because the saliva is more mucinous and the duct has a long upward course from the floor of the mouth. Nevertheless, stones do form in the parotid gland and the parotid ducts. Notably, most parotid duct calculi and submandibular duct calculi occur in mouths with excellent dental hygiene and mucosa. An ultrasound scan was performed. An initial ultrasound scan demonstrated a stone in the distal end of the right parotid duct with evidence of ductal dilation (eFig. 8.294). Assessment of the gland also demonstrated dilated ducts within the gland and evidence of intraparotid lymphadenopathy. The patient was treated with antibiotics. |
Anatomy_Gray_2861 | Anatomy_Gray | The patient was treated with antibiotics. A course of antibiotics was given to remove the bacteria that had produced the inflammation. On return to the doctor some days later the gland was normal in size and there was no evidence of inflammation or infection. An operation was necessary. The stone was at the distal end of the parotid duct and it would seem logical and straightforward to make a small incision at the sphincter in the buccal mucosa and deliver the stone, thus permitting the gland to drain normally. Unfortunately, in this patient’s case the gland was significantly destroyed by the chronic obstruction and bacterial infection. Furthermore, smaller calculi were also demonstrated in the gland at ultrasound. On direct questioning it appeared that the patient had had numerous attacks over the previous 4–5 years and it was decided that the parotid gland should be removed surgically. | Anatomy_Gray. The patient was treated with antibiotics. A course of antibiotics was given to remove the bacteria that had produced the inflammation. On return to the doctor some days later the gland was normal in size and there was no evidence of inflammation or infection. An operation was necessary. The stone was at the distal end of the parotid duct and it would seem logical and straightforward to make a small incision at the sphincter in the buccal mucosa and deliver the stone, thus permitting the gland to drain normally. Unfortunately, in this patient’s case the gland was significantly destroyed by the chronic obstruction and bacterial infection. Furthermore, smaller calculi were also demonstrated in the gland at ultrasound. On direct questioning it appeared that the patient had had numerous attacks over the previous 4–5 years and it was decided that the parotid gland should be removed surgically. |
Anatomy_Gray_2862 | Anatomy_Gray | The patient consented for removal of the parotid gland and a discussion of the possibility for loss of facial function and facial paralysis was had with the patient at this time. | Anatomy_Gray. The patient consented for removal of the parotid gland and a discussion of the possibility for loss of facial function and facial paralysis was had with the patient at this time. |
Anatomy_Gray_2863 | Anatomy_Gray | Within the parotid gland the facial nerve [VII] divides into its five terminal branches. At operation the gland is displayed and extremely careful dissection is necessary to peel away the parotid gland from the branches of the facial nerve [VII]. This procedure was made more difficult by the chronic inflammatory change within the gland. After the procedure the patient made a good recovery, though there was some mild paralysis of the whole of the right side of the face. Importantly, taste to the anterior two-thirds of the tongue was preserved. The taste fibers to the anterior two-thirds of the tongue travel in the chorda tympani nerve, which is a branch of the facial nerve [VII]. This nerve leaves the facial nerve [VII] to join the lingual nerve proximal to the parotid gland; therefore, any damage to the facial nerve [VII] within the parotid gland does not affect special sensation (taste). | Anatomy_Gray. Within the parotid gland the facial nerve [VII] divides into its five terminal branches. At operation the gland is displayed and extremely careful dissection is necessary to peel away the parotid gland from the branches of the facial nerve [VII]. This procedure was made more difficult by the chronic inflammatory change within the gland. After the procedure the patient made a good recovery, though there was some mild paralysis of the whole of the right side of the face. Importantly, taste to the anterior two-thirds of the tongue was preserved. The taste fibers to the anterior two-thirds of the tongue travel in the chorda tympani nerve, which is a branch of the facial nerve [VII]. This nerve leaves the facial nerve [VII] to join the lingual nerve proximal to the parotid gland; therefore, any damage to the facial nerve [VII] within the parotid gland does not affect special sensation (taste). |
Anatomy_Gray_2864 | Anatomy_Gray | Over the following week the paralysis improved and was likely due to nerve bruising during the procedure. The patient remained asymptomatic. A 60-year-old woman was brought to the emergency department with acute right-sided weakness, predominantly in the upper limb, which lasted for 24 hours. She made an uneventful recovery, but was extremely concerned about the nature of her illness and went to see her local doctor. A diagnosis of a transient ischemic attack (TIA) was made. A TIA is a neurological deficit resolving within 24 hours. It is a type of stroke. Neurological deficits may be permanent or transient. Most transient events resolve within 21 days; any failure of resolution beyond 21 days is an established stroke. An investigation into the cause of the TIA was undertaken. Eighty-five percent of all strokes result from cerebral infarction, of which most are due to embolization. A duplex Doppler scan of the carotid vessels was performed. | Anatomy_Gray. Over the following week the paralysis improved and was likely due to nerve bruising during the procedure. The patient remained asymptomatic. A 60-year-old woman was brought to the emergency department with acute right-sided weakness, predominantly in the upper limb, which lasted for 24 hours. She made an uneventful recovery, but was extremely concerned about the nature of her illness and went to see her local doctor. A diagnosis of a transient ischemic attack (TIA) was made. A TIA is a neurological deficit resolving within 24 hours. It is a type of stroke. Neurological deficits may be permanent or transient. Most transient events resolve within 21 days; any failure of resolution beyond 21 days is an established stroke. An investigation into the cause of the TIA was undertaken. Eighty-five percent of all strokes result from cerebral infarction, of which most are due to embolization. A duplex Doppler scan of the carotid vessels was performed. |
Anatomy_Gray_2865 | Anatomy_Gray | Eighty-five percent of all strokes result from cerebral infarction, of which most are due to embolization. A duplex Doppler scan of the carotid vessels was performed. The majority of emboli originate from plaques that develop at and around the carotid bifurcation. Emboli consist of platelet aggregates, cholesterol, and atheromatous debris. Emboli may also arise from the heart secondary to cardiac tumors or myocardial infarction. The lesion in the brain was on the left side. The motor cortex for the whole of the right side of the body is represented in the left motor strip of the brain, which sits on the precentral gyrus. The duplex Doppler ultrasound scan demonstrated a significant narrowing (stenosis) of the left internal carotid artery with evidence of plaque formation and abnormal flow in this region. The narrowing was approximately 90%. Treatment required an operation. | Anatomy_Gray. Eighty-five percent of all strokes result from cerebral infarction, of which most are due to embolization. A duplex Doppler scan of the carotid vessels was performed. The majority of emboli originate from plaques that develop at and around the carotid bifurcation. Emboli consist of platelet aggregates, cholesterol, and atheromatous debris. Emboli may also arise from the heart secondary to cardiac tumors or myocardial infarction. The lesion in the brain was on the left side. The motor cortex for the whole of the right side of the body is represented in the left motor strip of the brain, which sits on the precentral gyrus. The duplex Doppler ultrasound scan demonstrated a significant narrowing (stenosis) of the left internal carotid artery with evidence of plaque formation and abnormal flow in this region. The narrowing was approximately 90%. Treatment required an operation. |
Anatomy_Gray_2866 | Anatomy_Gray | Treatment required an operation. A carotid endarterectomy (removal of the stenosis and the atheromatous plaque) was planned. This procedure is indicated in the presence of an ulcerating plaque with stenosis. The procedure was carried out under general anesthetic and a curvilinear incision was placed in the left side of the neck. The common carotid, external carotid, and internal carotid arteries were displayed. All vessels were clamped and a shunt was placed from the common carotid artery into the internal carotid artery to maintain cerebral blood flow during the procedure. The internal carotid artery was opened and the plaque excised. | Anatomy_Gray. Treatment required an operation. A carotid endarterectomy (removal of the stenosis and the atheromatous plaque) was planned. This procedure is indicated in the presence of an ulcerating plaque with stenosis. The procedure was carried out under general anesthetic and a curvilinear incision was placed in the left side of the neck. The common carotid, external carotid, and internal carotid arteries were displayed. All vessels were clamped and a shunt was placed from the common carotid artery into the internal carotid artery to maintain cerebral blood flow during the procedure. The internal carotid artery was opened and the plaque excised. |
Anatomy_Gray_2867 | Anatomy_Gray | After the procedure the patient did extremely well and suffered no further cerebral events. However, a new medical student examined the patient the following day and demonstrated a number of interesting findings. These included altered skin sensation inferior to the left mandible, altered sensation on the left side of the soft palate, a paralyzed left vocal cord, inability to shrug the left shoulder, and a tongue that deviated to the left. The etiology of these injuries was due to localized nerve trauma. | Anatomy_Gray. After the procedure the patient did extremely well and suffered no further cerebral events. However, a new medical student examined the patient the following day and demonstrated a number of interesting findings. These included altered skin sensation inferior to the left mandible, altered sensation on the left side of the soft palate, a paralyzed left vocal cord, inability to shrug the left shoulder, and a tongue that deviated to the left. The etiology of these injuries was due to localized nerve trauma. |
Anatomy_Gray_2868 | Anatomy_Gray | The etiology of these injuries was due to localized nerve trauma. This constellation of neurological deficits can be accounted for by trauma to the nerves that are close to the carotid bifurcation. The changes in skin sensation can be accounted for by a neurapraxia due to damage to cervical nerves. The alteration in sensation in the soft palate is due to neurapraxia of the glossopharyngeal nerve [IX]. The paralyzed left cord results from neurapraxia of the recurrent laryngeal nerve, while the inability to shrug the shoulder is due to neurapraxia of the accessory nerve [XI]. Deviation of the tongue can be accounted for by damage to the hypoglossal nerve [XII]. Most of these changes are transient and are usually due to traction injuries during the surgical procedure. | Anatomy_Gray. The etiology of these injuries was due to localized nerve trauma. This constellation of neurological deficits can be accounted for by trauma to the nerves that are close to the carotid bifurcation. The changes in skin sensation can be accounted for by a neurapraxia due to damage to cervical nerves. The alteration in sensation in the soft palate is due to neurapraxia of the glossopharyngeal nerve [IX]. The paralyzed left cord results from neurapraxia of the recurrent laryngeal nerve, while the inability to shrug the shoulder is due to neurapraxia of the accessory nerve [XI]. Deviation of the tongue can be accounted for by damage to the hypoglossal nerve [XII]. Most of these changes are transient and are usually due to traction injuries during the surgical procedure. |
Anatomy_Gray_2869 | Anatomy_Gray | Most of these changes are transient and are usually due to traction injuries during the surgical procedure. A 33-year-old fit and well woman came to the emergency department complaining of double vision and pain behind her right eye. She had no other symptoms. On examination of the right eye the pupil was dilated. There was a mild ptosis. Testing of eye movement revealed that the eye turned down and out and the pupillary reflex was not present. These findings revealed that the patient had an ipsilateral third nerve palsy (palsy of the oculomotor nerve [III]). The oculomotor nerve [III] is the main motor nerve to the ocular and extra-ocular muscles. It arises from the midbrain and pierces the dura mater to run in the lateral wall of the cavernous sinus. The oculomotor nerve [III] leaves the cranial cavity and enters the orbit through the superior orbital fissure. Within this fissure it divides into its superior and inferior divisions. | Anatomy_Gray. Most of these changes are transient and are usually due to traction injuries during the surgical procedure. A 33-year-old fit and well woman came to the emergency department complaining of double vision and pain behind her right eye. She had no other symptoms. On examination of the right eye the pupil was dilated. There was a mild ptosis. Testing of eye movement revealed that the eye turned down and out and the pupillary reflex was not present. These findings revealed that the patient had an ipsilateral third nerve palsy (palsy of the oculomotor nerve [III]). The oculomotor nerve [III] is the main motor nerve to the ocular and extra-ocular muscles. It arises from the midbrain and pierces the dura mater to run in the lateral wall of the cavernous sinus. The oculomotor nerve [III] leaves the cranial cavity and enters the orbit through the superior orbital fissure. Within this fissure it divides into its superior and inferior divisions. |
Anatomy_Gray_2870 | Anatomy_Gray | The site of the nerve lesion needs to be assessed. Third nerve palsy may involve the nucleus of the oculomotor nerve [III], which typically spares the pupil and is painless. The pupillary reflexes are supplied from the autonomic fibers of the Edinger–Westphal nucleus, which pass through the ciliary ganglion. The lesion cannot be a primary oculomotor nerve [III] nuclear injury. As both the pupillary reflexes and vision are affected, the lesion is likely to be along the course of the oculomotor nerve [III]. Medical conditions such as diabetes mellitus and vascular disease may produce an isolated oculomotor nerve [III] injury, but they are not associated with pain. The lesion was caused by an aneurysm. | Anatomy_Gray. The site of the nerve lesion needs to be assessed. Third nerve palsy may involve the nucleus of the oculomotor nerve [III], which typically spares the pupil and is painless. The pupillary reflexes are supplied from the autonomic fibers of the Edinger–Westphal nucleus, which pass through the ciliary ganglion. The lesion cannot be a primary oculomotor nerve [III] nuclear injury. As both the pupillary reflexes and vision are affected, the lesion is likely to be along the course of the oculomotor nerve [III]. Medical conditions such as diabetes mellitus and vascular disease may produce an isolated oculomotor nerve [III] injury, but they are not associated with pain. The lesion was caused by an aneurysm. |
Anatomy_Gray_2871 | Anatomy_Gray | The lesion was caused by an aneurysm. One of the commonest causes of a third nerve palsy is pressure on the nerve from a posterior communicating artery aneurysm, which lies parallel to the nerve on the anterior aspect of the brainstem. As the aneurysm abuts the outside of the oculomotor nerve [III], it involves the parasympathetic fibers, which lead to a predominance of the loss of pupillary function over general function. The aneurysm was imaged with an angiogram. The patient initially underwent CT and MRI scanning. Currently, the definitive test for assessment of aneurysms arising from the circle of Willis and its branches is a digital subtraction angiogram. The angiogram demonstrated the posterior communicating artery aneurysm. The patient underwent surgery and made an excellent recovery. | Anatomy_Gray. The lesion was caused by an aneurysm. One of the commonest causes of a third nerve palsy is pressure on the nerve from a posterior communicating artery aneurysm, which lies parallel to the nerve on the anterior aspect of the brainstem. As the aneurysm abuts the outside of the oculomotor nerve [III], it involves the parasympathetic fibers, which lead to a predominance of the loss of pupillary function over general function. The aneurysm was imaged with an angiogram. The patient initially underwent CT and MRI scanning. Currently, the definitive test for assessment of aneurysms arising from the circle of Willis and its branches is a digital subtraction angiogram. The angiogram demonstrated the posterior communicating artery aneurysm. The patient underwent surgery and made an excellent recovery. |
Anatomy_Gray_2872 | Anatomy_Gray | A 10-year-old boy was brought to an ENT surgeon (ear, nose, and throat surgeon) with epistaxis (nose bleeding). The bleeding was associated with his nose picking habit. However, the bleeding was profuse and on two occasions required hospital admission and nasal packing. On inspection an indurated area was noted. The typical findings are an indurated area in the anterior inferior aspect of the nasal septum (Kiesselbach’s area). This is a very vascular area that has a considerable number of veins, which are often traumatized during nose picking. The patient underwent treatment. Typical treatment is cauterization of these prominent veins in Kiesselbach’s area, which is usually performed by a simple local analgesia and the application of silver nitrate. Unfortunately, the boy was involved in a fight the next day and again developed severe epistaxis, which again was difficult to control. | Anatomy_Gray. A 10-year-old boy was brought to an ENT surgeon (ear, nose, and throat surgeon) with epistaxis (nose bleeding). The bleeding was associated with his nose picking habit. However, the bleeding was profuse and on two occasions required hospital admission and nasal packing. On inspection an indurated area was noted. The typical findings are an indurated area in the anterior inferior aspect of the nasal septum (Kiesselbach’s area). This is a very vascular area that has a considerable number of veins, which are often traumatized during nose picking. The patient underwent treatment. Typical treatment is cauterization of these prominent veins in Kiesselbach’s area, which is usually performed by a simple local analgesia and the application of silver nitrate. Unfortunately, the boy was involved in a fight the next day and again developed severe epistaxis, which again was difficult to control. |
Anatomy_Gray_2873 | Anatomy_Gray | Unfortunately, the boy was involved in a fight the next day and again developed severe epistaxis, which again was difficult to control. Not only is there a rich venous plexus around Kiesselbach’s area, but there is also a significant arterial supply, which is provided from the nasal septal branches of the posterior and anterior ethmoidal arteries and the branches of the greater palatine artery. These are supplemented from the septal branches of the superior labial artery. In most cases treatment is conservative. | Anatomy_Gray. Unfortunately, the boy was involved in a fight the next day and again developed severe epistaxis, which again was difficult to control. Not only is there a rich venous plexus around Kiesselbach’s area, but there is also a significant arterial supply, which is provided from the nasal septal branches of the posterior and anterior ethmoidal arteries and the branches of the greater palatine artery. These are supplemented from the septal branches of the superior labial artery. In most cases treatment is conservative. |
Anatomy_Gray_2874 | Anatomy_Gray | In most cases treatment is conservative. Conservative treatment usually involves packing the nasal cavity until bleeding has stopped and correcting any bleeding abnormality. In patients with bleeding refractory to medical treatment a series of maneuvers have been employed, including ligating the anterior and posterior ethmoidal arteries through a medial incision in the canthus orbit, or by ligating other major arteries supplying the nasal cavity. Unfortunately, many of these procedures fail because of the rich and diverse origin of blood supply to the nasal cavity. Determination of the specific site of bleeding can be achieved radiologically. By placing a catheter from the femoral artery through the aorta and into the carotid circulation the sphenopalatine artery can be easily cannulated from the maxillary branch of the external carotid artery. Bleeding can usually be demonstrated and the vessel can be embolized using small particles. | Anatomy_Gray. In most cases treatment is conservative. Conservative treatment usually involves packing the nasal cavity until bleeding has stopped and correcting any bleeding abnormality. In patients with bleeding refractory to medical treatment a series of maneuvers have been employed, including ligating the anterior and posterior ethmoidal arteries through a medial incision in the canthus orbit, or by ligating other major arteries supplying the nasal cavity. Unfortunately, many of these procedures fail because of the rich and diverse origin of blood supply to the nasal cavity. Determination of the specific site of bleeding can be achieved radiologically. By placing a catheter from the femoral artery through the aorta and into the carotid circulation the sphenopalatine artery can be easily cannulated from the maxillary branch of the external carotid artery. Bleeding can usually be demonstrated and the vessel can be embolized using small particles. |
Anatomy_Gray_2875 | Anatomy_Gray | Fortunately in this young boy’s case, bleeding stopped after further medical management and he remained asymptomatic. A 30-year-old woman came to her doctor with a history of amenorrhea (absence of menses) and galactorrhea (the production of breast milk). She was not pregnant and appeared otherwise fit and well. Serum prolactin was measured. Prolactin is a hormone produced by the pituitary gland and necessary for the production of breast milk postpartum. This hormone was markedly elevated. Further clinical tests demonstrated visual field defects. The patient went to see an optometrist who performed a visual field assessment and demonstrated a reduction in the lateral aspects of the normal visual fields. This was bilateral and symmetrical—a bilateral temporal hemianopia. The visual pathways have now determined the site of the lesion. | Anatomy_Gray. Fortunately in this young boy’s case, bleeding stopped after further medical management and he remained asymptomatic. A 30-year-old woman came to her doctor with a history of amenorrhea (absence of menses) and galactorrhea (the production of breast milk). She was not pregnant and appeared otherwise fit and well. Serum prolactin was measured. Prolactin is a hormone produced by the pituitary gland and necessary for the production of breast milk postpartum. This hormone was markedly elevated. Further clinical tests demonstrated visual field defects. The patient went to see an optometrist who performed a visual field assessment and demonstrated a reduction in the lateral aspects of the normal visual fields. This was bilateral and symmetrical—a bilateral temporal hemianopia. The visual pathways have now determined the site of the lesion. |
Anatomy_Gray_2876 | Anatomy_Gray | The visual pathways have now determined the site of the lesion. Visual information from the temporal fields is projected onto the medial aspect of the retina bilaterally. The visual information from the medial aspects of the retina is carried in fibers that cross the midline through the optic chiasm to the opposite side. The lesion is in the area of the optic chiasm. Any disruption of the optic chiasm produces the field defect of bitemporal hemianopia. Tumors of the optic chiasm are unusual, though gliomas do occur. More frequently, compression of the optic chiasm by tumors in the vicinity is the usual cause for bitemporal hemianopia. A pituitary tumor was diagnosed. The optic chiasm is anterior and extremely close to the pituitary gland. Given that the patient is producing excessive amounts of prolactin (a pituitary tumor) and there is loss of the function of the chiasm, the most likely clinical explanation is an exophytic pituitary tumor compressing the optic chiasm. | Anatomy_Gray. The visual pathways have now determined the site of the lesion. Visual information from the temporal fields is projected onto the medial aspect of the retina bilaterally. The visual information from the medial aspects of the retina is carried in fibers that cross the midline through the optic chiasm to the opposite side. The lesion is in the area of the optic chiasm. Any disruption of the optic chiasm produces the field defect of bitemporal hemianopia. Tumors of the optic chiasm are unusual, though gliomas do occur. More frequently, compression of the optic chiasm by tumors in the vicinity is the usual cause for bitemporal hemianopia. A pituitary tumor was diagnosed. The optic chiasm is anterior and extremely close to the pituitary gland. Given that the patient is producing excessive amounts of prolactin (a pituitary tumor) and there is loss of the function of the chiasm, the most likely clinical explanation is an exophytic pituitary tumor compressing the optic chiasm. |
Anatomy_Gray_2877 | Anatomy_Gray | An MRI scan was performed and demonstrated a large tumor (macroadenoma) of the pituitary gland. Drug treatment was commenced and the tumor shrank (eFig. 8.295). The endocrinological effects of the prolactin secretion also stopped. Follow-up scans were performed. Over the ensuing few years the tumor shrank. Unfortunately, the patient again began to secrete prolactin and surgery was performed. A transsphenoidal approach was undertaken. With meticulous accuracy a series of very fine instruments was passed through the nasal cavity into the sphenoid bone. The bone was drilled and via this approach the pituitary gland was removed. Extreme care must be taken because on both sides of the pituitary gland is the cavernous sinus through which the internal carotid artery, oculomotor nerve [III], trochlear nerve [IV], trigeminal nerve [V], and abducent nerve [VI] pass. 1121.e2 1121.e1 Fig. 8.7, cont’d Skull. Conceptual Overview • Relationship to Other Regions Fig. 8.16, cont’d | Anatomy_Gray. An MRI scan was performed and demonstrated a large tumor (macroadenoma) of the pituitary gland. Drug treatment was commenced and the tumor shrank (eFig. 8.295). The endocrinological effects of the prolactin secretion also stopped. Follow-up scans were performed. Over the ensuing few years the tumor shrank. Unfortunately, the patient again began to secrete prolactin and surgery was performed. A transsphenoidal approach was undertaken. With meticulous accuracy a series of very fine instruments was passed through the nasal cavity into the sphenoid bone. The bone was drilled and via this approach the pituitary gland was removed. Extreme care must be taken because on both sides of the pituitary gland is the cavernous sinus through which the internal carotid artery, oculomotor nerve [III], trochlear nerve [IV], trigeminal nerve [V], and abducent nerve [VI] pass. 1121.e2 1121.e1 Fig. 8.7, cont’d Skull. Conceptual Overview • Relationship to Other Regions Fig. 8.16, cont’d |
Anatomy_Gray_2878 | Anatomy_Gray | 1121.e2 1121.e1 Fig. 8.7, cont’d Skull. Conceptual Overview • Relationship to Other Regions Fig. 8.16, cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d Table 8.5 Cranial nerves (see Table 8.4 for abbreviations)—cont’d In the clinic—cont’d Table 8.7 Muscles of the face—cont’d In the clinic—cont’d In the clinic—cont’d Fig. 8.149, cont’d In the clinic—cont’d Fig. 8.235, cont’d Fig. 8.239, cont’d Surface Anatomy • Visualizing Structures at the CIII/CIV and CVI Vertebral Levels Surface Anatomy • How to Locate the Cricothyroid Ligament Surface Anatomy • Major Features of the Face | Anatomy_Gray. 1121.e2 1121.e1 Fig. 8.7, cont’d Skull. Conceptual Overview • Relationship to Other Regions Fig. 8.16, cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d In the clinic—cont’d Table 8.5 Cranial nerves (see Table 8.4 for abbreviations)—cont’d In the clinic—cont’d Table 8.7 Muscles of the face—cont’d In the clinic—cont’d In the clinic—cont’d Fig. 8.149, cont’d In the clinic—cont’d Fig. 8.235, cont’d Fig. 8.239, cont’d Surface Anatomy • Visualizing Structures at the CIII/CIV and CVI Vertebral Levels Surface Anatomy • How to Locate the Cricothyroid Ligament Surface Anatomy • Major Features of the Face |
Anatomy_Gray_2879 | Anatomy_Gray | Surface Anatomy • Visualizing Structures at the CIII/CIV and CVI Vertebral Levels Surface Anatomy • How to Locate the Cricothyroid Ligament Surface Anatomy • Major Features of the Face Neuroanatomy and neuroscience are fields of science that seek to explain embryonic development, structural organization, and physiological function of the nervous system. Both fields work together to help identify the simple to the most complex questions of human sensory, motor, behavioral, and higher cognitive functions. The focus of this chapter is to introduce the basic structures and functions of the individual and systemic components of the human nervous system. Part I: Nervous system | Anatomy_Gray. Surface Anatomy • Visualizing Structures at the CIII/CIV and CVI Vertebral Levels Surface Anatomy • How to Locate the Cricothyroid Ligament Surface Anatomy • Major Features of the Face Neuroanatomy and neuroscience are fields of science that seek to explain embryonic development, structural organization, and physiological function of the nervous system. Both fields work together to help identify the simple to the most complex questions of human sensory, motor, behavioral, and higher cognitive functions. The focus of this chapter is to introduce the basic structures and functions of the individual and systemic components of the human nervous system. Part I: Nervous system |
Anatomy_Gray_2880 | Anatomy_Gray | Part I: Nervous system Organization of the human nervous system is structurally divided into the central nervous system (CNS) and peripheral nervous system (PNS) (eFig. 9.1). Components of the CNS are the brain and spinal cord, which are enclosed within the cranial cavity and vertebral column of the axial skeleton. Peripheral nervous system structures include cranial nerves, spinal nerves, autonomic nerves, and the enteric nervous system. | Anatomy_Gray. Part I: Nervous system Organization of the human nervous system is structurally divided into the central nervous system (CNS) and peripheral nervous system (PNS) (eFig. 9.1). Components of the CNS are the brain and spinal cord, which are enclosed within the cranial cavity and vertebral column of the axial skeleton. Peripheral nervous system structures include cranial nerves, spinal nerves, autonomic nerves, and the enteric nervous system. |
Anatomy_Gray_2881 | Anatomy_Gray | During the third week of development the outermost layer of the embryo—the ectoderm—thickens to form a neural plate (eFig. 9.2A). This plate develops a longitudinally running neural groove, which deepens so that it is flanked on either side by neural folds (eFig. 9.2B). These folds further develop and eventually fuse during a process called neurulation to form a long tubelike structure called the neural tube with an inner lumen called the neural canal (eFig. 9.3). Fusion of the tube starts at the midpoint and extends cranially and caudally so that the tube is fully formed by the fourth week. Continued proliferation of the cells at the cephalic end cause the neural tube to dilate and form the three primary brain vesicles (eFig. 9.4): the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain), which later give rise to the structures of the brain. Caudally, the neural tube lengthens and narrows to form the spinal cord. The neural canal forms the cavities of | Anatomy_Gray. During the third week of development the outermost layer of the embryo—the ectoderm—thickens to form a neural plate (eFig. 9.2A). This plate develops a longitudinally running neural groove, which deepens so that it is flanked on either side by neural folds (eFig. 9.2B). These folds further develop and eventually fuse during a process called neurulation to form a long tubelike structure called the neural tube with an inner lumen called the neural canal (eFig. 9.3). Fusion of the tube starts at the midpoint and extends cranially and caudally so that the tube is fully formed by the fourth week. Continued proliferation of the cells at the cephalic end cause the neural tube to dilate and form the three primary brain vesicles (eFig. 9.4): the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain), which later give rise to the structures of the brain. Caudally, the neural tube lengthens and narrows to form the spinal cord. The neural canal forms the cavities of |
Anatomy_Gray_2882 | Anatomy_Gray | and rhombencephalon (hindbrain), which later give rise to the structures of the brain. Caudally, the neural tube lengthens and narrows to form the spinal cord. The neural canal forms the cavities of the ventricular system in the brain and central canal of the spinal cord (eTable 9.1). The peripheral nervous system consists of cranial nerves, spinal nerves, spinal ganglia, the enteric system, and autonomic ganglia. The peripheral nervous system is formed by nerve fibers that extend out of the central nervous system and by neurons and their fibers that develop from migratory neural crest cells (eFig. 9.4A). Like the neural tube, neural crest cells originate from surface ectoderm and initially lie on each side of the developing CNS. | Anatomy_Gray. and rhombencephalon (hindbrain), which later give rise to the structures of the brain. Caudally, the neural tube lengthens and narrows to form the spinal cord. The neural canal forms the cavities of the ventricular system in the brain and central canal of the spinal cord (eTable 9.1). The peripheral nervous system consists of cranial nerves, spinal nerves, spinal ganglia, the enteric system, and autonomic ganglia. The peripheral nervous system is formed by nerve fibers that extend out of the central nervous system and by neurons and their fibers that develop from migratory neural crest cells (eFig. 9.4A). Like the neural tube, neural crest cells originate from surface ectoderm and initially lie on each side of the developing CNS. |
Anatomy_Gray_2883 | Anatomy_Gray | Several terms are used to identify the orientation and location of neural structures. The orientation nomenclature is quite simple in organisms such as fish and reptiles, which have a linear nervous system. For these animals, ventral (Latin for “belly”) is oriented toward the ground, dorsal (Latin for “back”) toward the sky, rostral (Latin for “beak”) toward the snout, and caudal (Latin for “tail) toward the tail (eFig. 9.5). Because humans are bipedal and maintain an erect posture, the nervous system makes an obligatory bend of 80 to 90 degrees at the midbrain–diencephalic junction. Because of this, directional references such as ventral, dorsal, rostral, and caudal have different meanings along different locations of the CNS structures (eFig. 9.6A). An additional set of terms that remain constant in their reference to orientation of nervous system structures are anterior, posterior, superior, and inferior. | Anatomy_Gray. Several terms are used to identify the orientation and location of neural structures. The orientation nomenclature is quite simple in organisms such as fish and reptiles, which have a linear nervous system. For these animals, ventral (Latin for “belly”) is oriented toward the ground, dorsal (Latin for “back”) toward the sky, rostral (Latin for “beak”) toward the snout, and caudal (Latin for “tail) toward the tail (eFig. 9.5). Because humans are bipedal and maintain an erect posture, the nervous system makes an obligatory bend of 80 to 90 degrees at the midbrain–diencephalic junction. Because of this, directional references such as ventral, dorsal, rostral, and caudal have different meanings along different locations of the CNS structures (eFig. 9.6A). An additional set of terms that remain constant in their reference to orientation of nervous system structures are anterior, posterior, superior, and inferior. |
Anatomy_Gray_2884 | Anatomy_Gray | When studied through imaging or in histopathology, the nervous system is observed in sections cut from one of three different planes: a coronal plane, which divides the nervous system into anterior and posterior parts; the sagittal plane, which is oriented at a right angle to the coronal plane and divides the nervous system into left and right parts; and a horizontal (also referred to as axial or transverse) plane, which divides the nervous system into superior and inferior parts (eFig. 9.6). Note that a sagittal plane passing through the midline may also be referred to as a midsagittal section, whereas a section taken just lateral to the midline is referred to as a parasagittal section. | Anatomy_Gray. When studied through imaging or in histopathology, the nervous system is observed in sections cut from one of three different planes: a coronal plane, which divides the nervous system into anterior and posterior parts; the sagittal plane, which is oriented at a right angle to the coronal plane and divides the nervous system into left and right parts; and a horizontal (also referred to as axial or transverse) plane, which divides the nervous system into superior and inferior parts (eFig. 9.6). Note that a sagittal plane passing through the midline may also be referred to as a midsagittal section, whereas a section taken just lateral to the midline is referred to as a parasagittal section. |
Anatomy_Gray_2885 | Anatomy_Gray | Nerve cells (neurons) and glial cells are the primary cellular components of the nervous system. Neurochemical signaling is predominantly carried out through a complex series of physiological connections between adjoining neurons. Glial cells participate in a constellation of functions that are vital for proper brain function. Their historically appreciated contribution to neuronal function has expanded to include recognition of their role in regulating the content of the extracellular space and regulation of neurotransmitters at the synaptic junction. | Anatomy_Gray. Nerve cells (neurons) and glial cells are the primary cellular components of the nervous system. Neurochemical signaling is predominantly carried out through a complex series of physiological connections between adjoining neurons. Glial cells participate in a constellation of functions that are vital for proper brain function. Their historically appreciated contribution to neuronal function has expanded to include recognition of their role in regulating the content of the extracellular space and regulation of neurotransmitters at the synaptic junction. |
Anatomy_Gray_2886 | Anatomy_Gray | Neurons consist of a cell body (or soma), which contains the cell nucleus, short processes called dendrites for receiving input from other neurons, and long processes called axons, which conduct signals away from the cell body (eTable 9.2). Depending on their location, neuronal morphology can be quite variable. The majority of mammalian neurons are multipolar, indicating that there are several dendrites from one end and a single axon that branches extensively at its terminus (eFig. 9.7). Some additional neuronal types are bipolar, unipolar, and pseudounipolar (eFig. 9.8). | Anatomy_Gray. Neurons consist of a cell body (or soma), which contains the cell nucleus, short processes called dendrites for receiving input from other neurons, and long processes called axons, which conduct signals away from the cell body (eTable 9.2). Depending on their location, neuronal morphology can be quite variable. The majority of mammalian neurons are multipolar, indicating that there are several dendrites from one end and a single axon that branches extensively at its terminus (eFig. 9.7). Some additional neuronal types are bipolar, unipolar, and pseudounipolar (eFig. 9.8). |
Anatomy_Gray_2887 | Anatomy_Gray | To prevent the loss of linear signal propagation, glial cells form a phospholipid-based layer of insulation called the myelin sheath along the length of the axon (eFig. 9.7). The myelin sheath is formed by oligodendrocytes in the CNS and Schwann cells in the PNS. Interspersed between the segments of myelin are exposed segments of the axon called nodes of Ranvier, which have a large population of voltage-gated ion channels. Presence of the ion channels facilitates rapid conduction of the action potential (a transient voltage change in the axonal membrane) from node to node in a process called saltatory conduction (eFig. 9.7). | Anatomy_Gray. To prevent the loss of linear signal propagation, glial cells form a phospholipid-based layer of insulation called the myelin sheath along the length of the axon (eFig. 9.7). The myelin sheath is formed by oligodendrocytes in the CNS and Schwann cells in the PNS. Interspersed between the segments of myelin are exposed segments of the axon called nodes of Ranvier, which have a large population of voltage-gated ion channels. Presence of the ion channels facilitates rapid conduction of the action potential (a transient voltage change in the axonal membrane) from node to node in a process called saltatory conduction (eFig. 9.7). |
Anatomy_Gray_2888 | Anatomy_Gray | Functionally, the nervous system is organized into a somatic nervous system and visceral nervous system. The somatic nervous system consists of nerves that carry conscious sensation from peripheral regions back to the CNS and nerves that exit the CNS to innervate voluntary (skeletal) muscles. In contrast, the visceral nervous system consists of nerves that carry sensory information into and motor (autonomic) innervation out of the CNS to regulate homeostatic functions. Further discussion of the somatic and visceral nervous systems will be presented within the context of the subsequent “Spinal Cord” section. Part II: Brain | Anatomy_Gray. Functionally, the nervous system is organized into a somatic nervous system and visceral nervous system. The somatic nervous system consists of nerves that carry conscious sensation from peripheral regions back to the CNS and nerves that exit the CNS to innervate voluntary (skeletal) muscles. In contrast, the visceral nervous system consists of nerves that carry sensory information into and motor (autonomic) innervation out of the CNS to regulate homeostatic functions. Further discussion of the somatic and visceral nervous systems will be presented within the context of the subsequent “Spinal Cord” section. Part II: Brain |
Anatomy_Gray_2889 | Anatomy_Gray | Part II: Brain Externally, the outer surface of the brain, or cerebral cortex, is composed of six layers of cell bodies referred to as gray matter. Internally, the myelinated axonal processes of these cells extend into the cerebral hemispheres. Because of the whitish appearance of these large bundles of myelinated axons, they are referred to as white matter. In the brain, gray matter is predominantly located on the cortical surface and the white matter runs deep inside the cerebral hemispheres; the opposite is true for the spinal cord, where the white matter is superficial to the gray matter. Topographically, the surface of the cerebral hemispheres has a series of elevations called gyri and infoldings referred to as sulci, both of which significantly increase the surface area of the brain. | Anatomy_Gray. Part II: Brain Externally, the outer surface of the brain, or cerebral cortex, is composed of six layers of cell bodies referred to as gray matter. Internally, the myelinated axonal processes of these cells extend into the cerebral hemispheres. Because of the whitish appearance of these large bundles of myelinated axons, they are referred to as white matter. In the brain, gray matter is predominantly located on the cortical surface and the white matter runs deep inside the cerebral hemispheres; the opposite is true for the spinal cord, where the white matter is superficial to the gray matter. Topographically, the surface of the cerebral hemispheres has a series of elevations called gyri and infoldings referred to as sulci, both of which significantly increase the surface area of the brain. |
Anatomy_Gray_2890 | Anatomy_Gray | Structurally, each cerebral hemisphere is divided into four major anatomical lobes: frontal, parietal, occipital, and temporal (eFig. 9.9A). The frontal lobes are located anteriorly and are separated from the more posterior parietal lobe by the central sulcus (sulcus of Rolando) (eFig. 9.9A). Laterally, the frontal lobe is separated from the temporal lobe by the lateral sulcus (fissure of Sylvius). Although there is no specific demarcation between the parietal and occipital lobe laterally, along the medial aspect of the hemispheres the two lobes are separated by the parieto-occipital sulcus (eFig. 9.9B). Along the midline, the cerebral hemispheres are separated from one another by the longitudinal fissure (interhemispheric fissure, sagittal fissure). Concealing a small area of cortex called the insula laterally are portions of the frontal, parietal, and temporal lobes collectively referred to as the operculum (Latin for “lid”) (eFig. 9.10). The insula represents fusion of the | Anatomy_Gray. Structurally, each cerebral hemisphere is divided into four major anatomical lobes: frontal, parietal, occipital, and temporal (eFig. 9.9A). The frontal lobes are located anteriorly and are separated from the more posterior parietal lobe by the central sulcus (sulcus of Rolando) (eFig. 9.9A). Laterally, the frontal lobe is separated from the temporal lobe by the lateral sulcus (fissure of Sylvius). Although there is no specific demarcation between the parietal and occipital lobe laterally, along the medial aspect of the hemispheres the two lobes are separated by the parieto-occipital sulcus (eFig. 9.9B). Along the midline, the cerebral hemispheres are separated from one another by the longitudinal fissure (interhemispheric fissure, sagittal fissure). Concealing a small area of cortex called the insula laterally are portions of the frontal, parietal, and temporal lobes collectively referred to as the operculum (Latin for “lid”) (eFig. 9.10). The insula represents fusion of the |
Anatomy_Gray_2891 | Anatomy_Gray | called the insula laterally are portions of the frontal, parietal, and temporal lobes collectively referred to as the operculum (Latin for “lid”) (eFig. 9.10). The insula represents fusion of the telencephalon and diencephalon and can be seen by gently prying open the lateral sulcus. | Anatomy_Gray. called the insula laterally are portions of the frontal, parietal, and temporal lobes collectively referred to as the operculum (Latin for “lid”) (eFig. 9.10). The insula represents fusion of the telencephalon and diencephalon and can be seen by gently prying open the lateral sulcus. |
Anatomy_Gray_2892 | Anatomy_Gray | The path to and from the cerebral cortex is achieved through various white matter pathways coursing through the spinal cord, brainstem, and cerebral hemispheres. Beneath the gray matter of the cortical surface is an expansion of white matter referred to as the corona radiata. This white matter pathway condenses to form the internal capsule, a V-shaped structure when viewed in horizontal sections that contains axons traversing to and from various cortical and deep nuclear structures (eFig. 9.11). The internal capsule is divided into three parts based on connections to different parts of the cortex and underlying structures. The most anterior portion of this white matter pathway is the anterior limb, which is bounded medially by the head of the caudate and laterally by the globus pallidus and putamen. The anterior limb transitions into the genu (Latin for “knee”) at the level of the interventricular foramen (of Monro) and completes its course as the posterior limb, situated lateral to | Anatomy_Gray. The path to and from the cerebral cortex is achieved through various white matter pathways coursing through the spinal cord, brainstem, and cerebral hemispheres. Beneath the gray matter of the cortical surface is an expansion of white matter referred to as the corona radiata. This white matter pathway condenses to form the internal capsule, a V-shaped structure when viewed in horizontal sections that contains axons traversing to and from various cortical and deep nuclear structures (eFig. 9.11). The internal capsule is divided into three parts based on connections to different parts of the cortex and underlying structures. The most anterior portion of this white matter pathway is the anterior limb, which is bounded medially by the head of the caudate and laterally by the globus pallidus and putamen. The anterior limb transitions into the genu (Latin for “knee”) at the level of the interventricular foramen (of Monro) and completes its course as the posterior limb, situated lateral to |
Anatomy_Gray_2893 | Anatomy_Gray | and putamen. The anterior limb transitions into the genu (Latin for “knee”) at the level of the interventricular foramen (of Monro) and completes its course as the posterior limb, situated lateral to the thalamus and medial to the globus pallidus and putamen. In addition to this more vertical stream of axonal connections is the horizontally running corpus callosum. The corpus callosum (eFig. 9.12) is formed by myelinated axons horizontally linking the two cerebral hemispheres to one another, and it is divided into a rostrum, genu, body, and splenium (eFig. 9.12). | Anatomy_Gray. and putamen. The anterior limb transitions into the genu (Latin for “knee”) at the level of the interventricular foramen (of Monro) and completes its course as the posterior limb, situated lateral to the thalamus and medial to the globus pallidus and putamen. In addition to this more vertical stream of axonal connections is the horizontally running corpus callosum. The corpus callosum (eFig. 9.12) is formed by myelinated axons horizontally linking the two cerebral hemispheres to one another, and it is divided into a rostrum, genu, body, and splenium (eFig. 9.12). |
Anatomy_Gray_2894 | Anatomy_Gray | The ventricular system is derived from the inner lumen of the developing neural tube. As the brain continues to grow, the caverns and canals of the ventricular system adapt to the shape of the cerebral hemispheres, diencephalon, pons, medulla, and cerebellum, which form the surrounding walls (eFig. 9.13). Inferior and lateral to the corpus callosum are two large, fluid-filled cavities that represent the beginning of the ventricular system. These most rostral cavities are the two C-shaped lateral ventricles, located within the cerebral hemispheres (eFig. 9.14). As the lateral ventricles extend through all of the lobes of the cerebral hemispheres, they are divided into five named parts. In the frontal lobe is the anterior (frontal) horn, which transitions into the body within the frontal and parietal lobes (eFig. 9.15). Projecting into the occipital lobe is the posterior (occipital) horn (eFig. 9.15). A final horn extends inferiorly and anteriorly as the inferior (temporal) horn in the | Anatomy_Gray. The ventricular system is derived from the inner lumen of the developing neural tube. As the brain continues to grow, the caverns and canals of the ventricular system adapt to the shape of the cerebral hemispheres, diencephalon, pons, medulla, and cerebellum, which form the surrounding walls (eFig. 9.13). Inferior and lateral to the corpus callosum are two large, fluid-filled cavities that represent the beginning of the ventricular system. These most rostral cavities are the two C-shaped lateral ventricles, located within the cerebral hemispheres (eFig. 9.14). As the lateral ventricles extend through all of the lobes of the cerebral hemispheres, they are divided into five named parts. In the frontal lobe is the anterior (frontal) horn, which transitions into the body within the frontal and parietal lobes (eFig. 9.15). Projecting into the occipital lobe is the posterior (occipital) horn (eFig. 9.15). A final horn extends inferiorly and anteriorly as the inferior (temporal) horn in the |
Anatomy_Gray_2895 | Anatomy_Gray | parietal lobes (eFig. 9.15). Projecting into the occipital lobe is the posterior (occipital) horn (eFig. 9.15). A final horn extends inferiorly and anteriorly as the inferior (temporal) horn in the temporal lobe (eFig. 9.15). Near the splenium of the corpus callosum, the body, posterior, and inferior horns come together at the atrium/trigone of the lateral ventricles (eFig. 9.15). Lining most of the ventricles is the choroid plexus (eFig. 9.16), a series of modified ependymal cells responsible for producing 0.5 L of cerebrospinal fluid (CSF) a day in adults. | Anatomy_Gray. parietal lobes (eFig. 9.15). Projecting into the occipital lobe is the posterior (occipital) horn (eFig. 9.15). A final horn extends inferiorly and anteriorly as the inferior (temporal) horn in the temporal lobe (eFig. 9.15). Near the splenium of the corpus callosum, the body, posterior, and inferior horns come together at the atrium/trigone of the lateral ventricles (eFig. 9.15). Lining most of the ventricles is the choroid plexus (eFig. 9.16), a series of modified ependymal cells responsible for producing 0.5 L of cerebrospinal fluid (CSF) a day in adults. |
Anatomy_Gray_2896 | Anatomy_Gray | From the lateral ventricles, CSF flows through the interventricular foramen (of Monro) to the slitlike third ventricle, which is surrounded by the thalamus and hypothalamus (eFig. 9.15). The third ventricle communicates with the fourth ventricle via the cerebral aqueduct (aqueduct of Sylvius), which courses through the midbrain (eFig. 9.15). Surrounded by the pons and medulla anteriorly and the cerebellum posteriorly, the fourth ventricle sends CSF out of the ventricular system and into the subarachnoid space via the lateral foramina of Luschka and midline foramen of Magendie (eFig. 9.15). | Anatomy_Gray. From the lateral ventricles, CSF flows through the interventricular foramen (of Monro) to the slitlike third ventricle, which is surrounded by the thalamus and hypothalamus (eFig. 9.15). The third ventricle communicates with the fourth ventricle via the cerebral aqueduct (aqueduct of Sylvius), which courses through the midbrain (eFig. 9.15). Surrounded by the pons and medulla anteriorly and the cerebellum posteriorly, the fourth ventricle sends CSF out of the ventricular system and into the subarachnoid space via the lateral foramina of Luschka and midline foramen of Magendie (eFig. 9.15). |
Anatomy_Gray_2897 | Anatomy_Gray | Within the bony encasement of the skull and vertebral column, the CNS is surrounded by three concentric, connective tissue coverings called meninges (from Greek word meninx for “membrane”), which act to support and stabilize the brain and spinal cord. The focus of this section will be on the cranial meninges. The spinal meninges, which have a slightly different configuration, will be discussed in the “Spinal Cord” section. | Anatomy_Gray. Within the bony encasement of the skull and vertebral column, the CNS is surrounded by three concentric, connective tissue coverings called meninges (from Greek word meninx for “membrane”), which act to support and stabilize the brain and spinal cord. The focus of this section will be on the cranial meninges. The spinal meninges, which have a slightly different configuration, will be discussed in the “Spinal Cord” section. |
Anatomy_Gray_2898 | Anatomy_Gray | The outermost covering is the dura (Latin for “hard”) mater (Latin for “mother”), a tough, fibrous sheet composed of two layers. The outer periosteal layer is adherent to the skull, and the inner meningeal layer lies against the underlying arachnoid mater (eFig. 9.17). Although these two layers are closely adherent to one another, they do separate in some regions to form dural venous sinuses, which receive cerebral venous drainage (eFig. 9.18). The anatomy of the venous sinuses will be discussed in the “Cerebral Vasculature” section. Two potential spaces exist as the epidural (extradural) space, superficial to the periosteal layer, and subdural space, deep to the meningeal dural layer. These spaces can become filled with blood during vascular trauma (eTable 9.3). Within the cranial cavity, the meningeal layer of dura mater folds in on itself in several areas to form dural reflections, or septa. These reflections are known as the falx (Latin for “sickle”) cerebri between the cerebral | Anatomy_Gray. The outermost covering is the dura (Latin for “hard”) mater (Latin for “mother”), a tough, fibrous sheet composed of two layers. The outer periosteal layer is adherent to the skull, and the inner meningeal layer lies against the underlying arachnoid mater (eFig. 9.17). Although these two layers are closely adherent to one another, they do separate in some regions to form dural venous sinuses, which receive cerebral venous drainage (eFig. 9.18). The anatomy of the venous sinuses will be discussed in the “Cerebral Vasculature” section. Two potential spaces exist as the epidural (extradural) space, superficial to the periosteal layer, and subdural space, deep to the meningeal dural layer. These spaces can become filled with blood during vascular trauma (eTable 9.3). Within the cranial cavity, the meningeal layer of dura mater folds in on itself in several areas to form dural reflections, or septa. These reflections are known as the falx (Latin for “sickle”) cerebri between the cerebral |
Anatomy_Gray_2899 | Anatomy_Gray | the meningeal layer of dura mater folds in on itself in several areas to form dural reflections, or septa. These reflections are known as the falx (Latin for “sickle”) cerebri between the cerebral hemispheres, as the tentorium cerebelli between the cerebral hemispheres and cerebellum, and as the falx cerebelli between the cerebellar hemispheres (eFig. 9.17). A smaller reflection, the diaphragm sellae, covers the pituitary fossa and underlying pituitary gland. | Anatomy_Gray. the meningeal layer of dura mater folds in on itself in several areas to form dural reflections, or septa. These reflections are known as the falx (Latin for “sickle”) cerebri between the cerebral hemispheres, as the tentorium cerebelli between the cerebral hemispheres and cerebellum, and as the falx cerebelli between the cerebellar hemispheres (eFig. 9.17). A smaller reflection, the diaphragm sellae, covers the pituitary fossa and underlying pituitary gland. |
Subsets and Splits