Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / @xirurgi_2025 / @xirurgi_2025 - 686 - файл
.pdf
CHAPTER 6 The Nervous System
Posterior median
Anterior horn
fissure
column
Posterior white
Dorsal root
Mixed nerve
movement)
Fasciculus
temperature,
Descending tracts Ascending tracts
151
Substantia
gelatinosa
Posterior
horn
Lateral
horn
Lateral white
column
Central
canal
septum
Anterior median
column
Anterior white
Dorsal root
ganglion
Dorsal
ramus
trunk
Ventral
ramus
Grey matter
Ventral root
Fig. 6.7 Spinal cord in cross-section showing grey and white matter and spinal nerve roots.
Posterior columns
– direct (position,
vibration, touch)
Posterior
spinocerebellar
tract
Anterior
spinocerebellar
tract
Equilibrium
Crossed
pyramidal
tract
(voluntary
gracilis
Fasciculus
cuneatus
Direct
pyramidal
tract
(voluntary
movement)
Lateral
spinothalamic
tract – crossed
Anterior
spinothalamic
tract – direct
Pain,
touch
Fig. 6.8 Cross-section of the spinal cord showing important ascending and descending tracts.
• bres in dorsal columns are uncrossed
• synapse in gracile and cuneate nuclei in medulla
• second-order bres cross in the sensory decussation
whence they synapse in the thalamus
• third-order bres pass to the sensory cortex
• some bres pass from medulla to cerebellum along
the inferior cerebellar peduncle.
• Posterior spinal arteries supply the posterior grey columns and dorsal columns on either side.
• Spinal artery reinforced at segmental level by radicular
arteries, i.e. branches of the ascending cervical, cervical
part of the vertebral, posterior intercostal and lumbar
arteries.
• Radicular arteries may be compromised in resection of
segments of the aorta in aneurysm surgery.
Blood Supply of the Spinal Cord
• Anterior and posterior spinal arteries from the vertebral
arteries.
• Anterior spinal arteries supply the whole of the cord in
front of the posterior grey columns.
Clinical Points
A cross-section of the spinal cord demonstrating the representation of the various areas in the spinal tracts is shown
in Fig. 6.9.
152
Spinothalamic
Posterior
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
SECTION I Anatomy
S
L
T
C
L
T
C
S
L
T
S
C
columns
Lateral
corticospinal
tract
tract
Fig. 6.9 Cross-section of the spinal cord showing
the representation of the cervical (C), thoracic (T),
lumbar (L) and sacral (S) areas in the various spinal
tracts.
A B
C D
Fig. 6.10 Incomplete spinal cord injury. (A) Anterior
cord syndrome. (B) Central cord syndrome. (C)
Posterior cord syndrome. (D) Brown–Séquard syndrome. The dark shaded area shows the region of
the cord involved.
Complete Transection of Spinal Cord
• Total loss of voluntary movement distal to level of transection; this loss is irreversible.
• Loss of all sensation from those areas which depend on
ascending pathways crossing the site of injury.
Incomplete Spinal Cord Injury (Fig. 6.10)
• Anterior cord syndrome:
• associated with exion/rotation injuries producing
anterior dislocation or compression fracture of vertebral body with bone encroaching on the vertebral canal
• loss of power below level of lesion
• loss of pain and temperature below the lesion
• in addition to direct damage, the anterior spinal
artery may be compressed
• the dorsal columns remain intact so that touch and
proprioception are not aected.
• Central cord syndrome:
• occurs in syringomyelia and centrally placed tumours
• initially involves decussating spinothalamic bres so
that pain and temperature are lost below the lesion
• later the lateral corticospinal tract is involved, with
the more centrally placed cervical tract supplying the
arm being involved more than the peripheral tracts
supplying the legs. Classically there is accid weakness of the arms, but because the distal leg and sacral
motor and sensory bres are spared, perianal sensation and some leg movement and sensation may be
preserved
• proprioception and ne touch are preserved in the
dorsal columns until late.
• Posterior cord syndrome:
• seen in hyperextension injuries with fractures of the
posterior elements of the vertebra
• loss of proprioception with profound ataxia with
unsteady and faltering gait
• usually good power and pain and temperature sensation below the lesion.
• Brown–Séquard syndrome:
• hemisection of the cord
• stab injury or damage to lateral mass of vertebrae
• paralysis on aected side below lesion (pyramidal
tract)
• loss of proprioception and ne discrimination (dorsal columns) on aected side below lesion
• loss of pain and temperature on opposite side below
lesion (normal on aected side because of decussation below level of hemisection)
• therefore the uninjured side has good power, but
absent sensation to pinprick and temperature.
• Cauda equina syndrome:
• compression of lumbosacral nerve roots below the
conus medullaris
• caused by bony compression or disc protrusion in
the lumbosacral area
• lower motor neuron lesion
• bowel and bladder dysfunction together with leg
numbness and weakness.
THE MENINGES
• Dura mater.
• Arachnoid mater.
• Pia mater.
CHAPTER 6 The Nervous System
153
Dura Mater
• Outer endosteal layer.
• Inner meningeal layer.
• Meningeal layer continuous into vertebral canal as dura
covering spinal cord.
• e two layers are fused together except where they
form the walls of dural venous sinuses.
• Folds of dura mater divide the cranial cavity into
compartments.
• ese folds are:
• falx cerebri
• tentorium cerebelli
• falx cerebelli.
Falx Cerebri
• Lies between the two cerebral hemispheres.
• Attached anteriorly to crista galli.
• Attached posteriorly to tentorium cerebelli.
• Superior sagittal sinus lies in its attached superior
border.
• Inferior sagittal sinus lies in its free inferior border.
• e straight sinus is seen where the falx meets the tentorium cerebelli.
Tentorium Cerebelli
• Attached anteriorly to the posterior clinoid process of
sphenoid bone.
• Attachment runs posteromedially along the superior
border of the petrous temporal bone where superior
petrosal sinuses enclosed.
• Where latter empties into transverse sinus, attached
border runs posteromedially along the lips of the groove
for the transverse sinus to reach the internal occipital
protuberance.
• It then continues on the opposite side of the skull to
reach the other posterior clinoid process.
• Free border of tentorium is attached to anterior clinoid
processes.
• Runs posterior and medially, curving round the midbrain, forming tentorial notch.
• Just behind the apex of the petrous temporal bone, the
inferior layer prolongs into the middle cranial fossa as
the trigeminal cave.
Falx Cerebelli
• Lies between the two lateral lobes of the cerebellum.
• Lies below the tentorium in the posterior cranial fossa.
Diaphragma Sellae
• Fold of dura forming the roof of the pituitary fossa.
• Covers the pituitary gland and has an opening through
which the infundibulum passes.
Arachnoid Mater
• Separated from dura by subdural space.
• e subarachnoid space contains cerebrospinal uid
(CSF) and major blood vessels.
• Arachnoid and subarachnoid spaces extend into vertebral canal to the level of the second piece of the
sacrum.
• Deep surface of the arachnoid projects into the venous
sinuses to form arachnoid villi; these are most numerous along the superior sagittal sinus. Collections of
arachnoid villi are known as arachnoid granulations.
• Arachnoid granulations are sites of reabsorption of CSF
into superior sagittal sinus and probably other dural
sinuses.
Subarachnoid Cisterns
• Subarachnoid space varies in size as arachnoid follows
surface of dura and pia follows surface of brain.
• is arrangement gives rise to cisterns:
• cerebellomedullary cistern (cisterna magna): poste-
rior to medulla below cerebellum
• pontine cistern: anterior to pons
• interpeduncular cistern: between cerebral peduncles
and optic chiasma—contains circle of Willis and cranial nerves III and IV.
Pia Mater
• Closely follows surface of brain.
• Dips down to sulci.
• Blood vessels enter brain in a sleeve of pia mater.
• At the choroid ssure of lateral ventricles and the roof
of the third and fourth ventricles, the pia is invaginated
by blood vessels to form the tela choroidea and choroid
plexus.
Production and Circulation of CSF
• Produced by choroid plexus in all four ventricles.
• Flows from lateral ventricles to third ventricle to cerebral aqueduct to fourth ventricle to subarachnoid
space.
• Absorbed into venous system through arachnoid granulations along dural venous sinuses.
• e interventricular foramen (of Monro) connects the
lateral ventricle to third ventricle.
• e fourth ventricle has three openings on its roof
which connect it to the subarachnoid space:
• the foramen of Magendie in the midline
• the paired foramina of Luschka laterally.
• rough these, CSF ows from the ventricular system
into the subarachnoid space.
• Total volume about 100–150 mL.
• Pressure 8–10 cmH2O.
154
Anterior cerebral artery
communicating
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
SECTION I Anatomy
Blood Supply to the Brain (See Fig. 5.22)
• Two vertebral arteries.
• Two internal carotid arteries.
Vertebral Arteries
• Enter cranial cavity via foramen magnum.
• Lie in subarachnoid space.
• Unite at lower border of pons to form basilar artery.
Branches
• Posterior spinal artery.
• Anterior spinal artery.
• Posterior inferior cerebellar artery.
Basilar Artery
Branches
• Anterior inferior cerebellar.
• Labyrinthine artery.
• Pontine arteries.
• Superior cerebellar arteries.
• Posterior cerebral artery (terminal branches of basilar
artery) supplies visual area of occipital lobe; occlusion
causes blindness in contralateral visual eld.
Internal Carotid Arteries
Branches
• Posterior communicating artery.
• Anterior cerebral artery.
• Middle cerebral artery.
• Anterior choroidal artery.
Middle Cerebral Artery
• Larger of terminal branches of internal carotid artery.
• Supplies lateral surface of frontal, parietal and temporal
lobes (except narrow strips supplied by anterior cerebral
artery).
• Occlusion results in contralateral motor and sensory
paralysis of face and arm.
Anterior
communicating
artery
Posterior
artery
Basilar artery
Anterior inferior
cerebellar artery
Posterior inferior
cerebellar artery
Fig. 6.11 The circle of Willis. The central arteries sup-
ply the corpus striatum, internal capsule, diencephalon and midbrain.
Internal carotid artery
Central arteries
Posterior cerebral artery
Pontine
}
branches
Labyrinthine artery
Vertebral artery
Middle cerebral artery
Superior cerebellar
artery
Venous Drainage of Brain
e veins lie alongside the arteries in the subarachnoid
space. ey pierce the pia mater and drain into the dural
venous sinuses. e major veins are:
• superior cerebral veins
• supercial middle cerebral vein
• basal vein
• great cerebral vein.
Circle of Willis (Fig. 6.11)
• Formed by the two vertebral and two internal carotid
arteries on the inferior surface of the brain.
• Each half of the circle is formed by:
• anterior communicating artery
• anterior cerebral artery
• internal carotid artery
• posterior communicating artery
• posterior cerebral artery.
• Despite interconnection, there is only minimal mixing
of blood passing through the arteries.
• When one artery is blocked the arterial circle may provide collateral circulation.
Dural Venous Sinuses (Fig. 6.12)
• Situated within the dura mater.
• Devoid of valves.
• Drain eventually into internal jugular vein.
e cranial venous sinuses are:
• superior sagittal sinus
• inferior sagittal sinus
• straight sinus
• transverse sinus
• sigmoid sinus
• conuence of sinuses
• occipital sinus
• cavernous sinus.
Inferior sagittal sinus
Inferior petrosal sinus
Right transverse sinus
Superior sagittal sinus
Superior petrosal sinus
CHAPTER 6 The Nervous System
Falx cerebri
155
Fig. 6.12 The venous sinuses.
• Commences at crista galli.
• Courses backwards along attached border of falx cerebri.
• Usually becomes continuous with right transverse sinus
• Venous lacunae lie along its course and open into the
• Sinus and lacunae are invaginated by arachnoid
• Superior cerebral veins drain into superior sagittal sinus.
• Lies along inferior border of falx cerebri.
• Receives cerebral veins from medial surface of
• Joins great cerebral vein to form straight sinus.
• Formed by union of inferior sagittal sinus and great
• Lies in attachment of falx cerebri to tentorium cerebelli.
• Usually becomes continuous with le transverse sinus
• Lies in groove on inner surface of occipital bone along
• On reaching petrous temporal bone it curves down-
Sphenoparietal sinus
Cavernous sinus
Superior sagittal sinus
at the internal occipital protuberance.
sinus.
granulations.
Inferior sagittal sinus
hemispheres.
Straight sinus
cerebral vein.
near internal occipital protuberance.
Transverse sinus
posterior attachment of tentorium cerebelli.
wards into posterior cranial fossa to follow a curved
course as sigmoid sinus.
Straight sinus
Tentorium cerebelli
Sigmoid sinus
• Passes through jugular foramen.
• Becomes continuous with internal jugular vein.
Confluence of sinuses
• Formed by the two transverse sinuses near the internal
occipital protuberance.
Occipital sinus
• Small sinus extending from foramen magnum.
• Drains into conuence of sinuses.
• Lies along falx cerebelli and connects vertebral venous
plexuses to transverse sinus.
Cavernous sinus (Fig. 6.13)
• One on each side.
• Situated on body of sphenoid bone.
• Extends from superior orbital ssure to apex of petrous
temporal bone.
• Relations:
• medially: pituitary gland and sphenoid sinus
• laterally: temporal lobe of brain.
• Internal carotid artery and abducens nerve (VI) pass
through it.
• On the lateral wall from above down are:
• oculomotor nerve (III)
• trochlear nerve (IV)
• ophthalmic nerve (V)
• maxillary nerve (V).
• Ophthalmic veins drain into the anterior part of sinus.
156
Optic nerve
Hypophysis cerebri
Oculomotor nerve
Ophthalmic nerve
Abducens nerve
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
SECTION I Anatomy
Diaphragma sellae
Hypophyseal stalk
Cavernous sinus
Trochlear nerve
Pia
Fig. 6.13 The cavernous sinus.
• Posteriorly the sinus drains into the transverse or
• Emissary veins passing through the foramina of the
• e two sinuses are connected by anterior and posterior
Clinical Points
• Cavernous sinus thrombosis may occur as a result of
• Blockage of the venous drainage of the orbit consequent
CRANIAL NERVES
I Olfactory Nerve
• Axons from olfactory mucosa in nasal cavity pass
Sphenoid air sinus
Internal carotid artery
sigmoid sinus through superior and inferior petrosal
sinuses.
middle cranial fossa connect the cavernous sinus to the
pterygoid plexus and facial veins.
intercavernous sinuses lying in front of and behind the
pituitary gland, respectively.
spread of infection from the lips and face via the anterior facial and ophthalmic veins, or from deep infections via the pterygoid venous plexus, all of which drain
into the sinus.
on cavernous sinus thrombosis results in a characteristic
clinical picture:
• oedema of the conjunctiva and eyelids
• exophthalmos with transmitted pulsations from the
internal carotid artery
• ophthalmoplegia due to pressure on the contained
cranial nerves
• ophthalmoscopy demonstrates papilloedema and
retinal haemorrhages.
through the cribriform plate of the ethmoid bone to end
in the olfactory bulb.
Arachnoid
Maxillary nerve
• A cu of dura, arachnoid and pia mater surrounds each
bundle of nerves.
• Synapse with mitral cells in olfactory bulb.
• Axons of mitral cells pass backwards in the olfactory
tract to terminate in the cortex of the uncus.
Clinical Points
• Head injuries involving fractures in the anterior cranial
fossa may sever the olfactory nerves, resulting in bilateral anosmia. In addition, fractures in the anterior cranial fossa may also cause CSF rhinorrhoea.
• Unilateral anosmia may be a sign of frontal lobe
tumours.
• Olfactory cortex consists of the uncus and anterior perforated substance.
• Tumours in the region of the uncus may result in an
‘uncinate t’, characterized by olfactory hallucinations
associated with impairment of consciousness and involuntary chewing movements.
II Optic Nerve (Fig. 6.14)
• Commences at lamina cribrosa, where axons of ganglion cells of retina pierce sclera.
• Covered by dura, arachnoid and pia mater, it runs posteromedially in the orbit to enter the optic canal.
• Accompanied by the ophthalmic artery.
• Reaches the optic groove on the dorsum of the body of
sphenoid bone.
• Fibres from medial half of retina, i.e. temporal visual
eld, cross over in the optic chiasma to the optic tract of
the opposite side.
• Fibres from the lateral half of the retina, i.e. nasal visual
eld, pass backwards in the optic tract of the same side.
CHAPTER 6 The Nervous System
Medial half of retina
Optic
geniculate
cortex
157
Optic
nerve
Lateral half
of retina
Optic
chiasm
tract
Lateral
body
Visual
Fig. 6.14 The visual pathways.
Optic
radiation
• Optic tract passes posterolaterally from the optic chiasma.
• e majority of bres in the optic tract end in the lateral
geniculate body of thalamus.
• A small proportion of optic tract bres bypass the lateral geniculate body, ending in the superior colliculus
or pretectal nucleus. ese bres subserve pupillary,
ocular and head and neck reexes (aerent limb of light
reexes).
• From the lateral geniculate bodies, bres of the optic
radiation pass laterally and backwards to the visual cortex of the occipital lobe.
• e upper half of the retina is represented in the upper
lip of the calcarine ssure, the lower half on the lower
lip.
Clinical Points
• Lesions of the optic nerve result in ipsilateral blindness.
• Lesions of the optic tract and central visual pathway
result in contralateral homonymous hemianopia.
• Lesions of the optic chiasma (e.g. from expanding pituitary lesions) will cause bitemporal hemianopia (loss of
vision of both temporal elds).
• inferior oblique
• levator palpebrae superioris.
2. Preganglionic parasympathetic bres supplying the
sphincter of the pupil via the ciliary ganglion.
• Somatic eerent nucleus (ocular muscles and
Edinger–Westphal nucleus; parasympathetic) lie
in midbrain at level of superior colliculus.
• Oculomotor nerve emerges between cerebral
peduncles.
• Passes forwards between superior cerebellar
artery and posterior cerebral artery.
• Pierces dura to lie on lateral wall of cavernous
sinus.
• Divides into superior and inferior branch before
entering into superior orbital ssure.
• Superior division supplies superior rectus and
levator palpebrae superioris.
• Inferior division supplies medial rectus, inferior
rectus and inferior oblique.
• Parasympathetic bres leave the branch to the
inferior oblique to synapse in the ciliary ganglion
(lies at the apex of the orbit just lateral to the optic
nerve).
• Postganglionic bres pass to ciliary muscles and
constrictor pupillae via the short ciliary nerves.
• Stimulation of the nerve results in pupillary con-
striction and accommodation of the lens.
Clinical Points
• Complete division of the nerve results in:
• ptosis, due to paralysis of levator palpebrae superioris
• divergent squint, caused by unopposed action of lateral rectus and superior oblique
• dilatation of the pupil, caused by unopposed action
of dilator pupillae (supplied by sympathetic bres in
the long ciliary branches in the nasociliary nerve)
• loss of accommodation and light reexes, due to
paralysis of ciliary muscles and constrictor pupillae
• diplopia.
• Oculomotor nerve may be paralysed by:
• aneurysm of posterior cerebral, superior cerebellar
and posterior communicating arteries
• raised intracranial pressure associated with herniation of uncus into tentorial notch
• tumours in region of sella turcica.
III Oculomotor Nerve
• Two main components:
1. Somatic motor bres supplying:
• superior rectus
• inferior rectus
• medial rectus
IV Trochlear Nerve
• Smallest cranial nerve.
• Supplies superior oblique muscle.
• Nucleus lies at level of inferior colliculus.
• Fibres pass dorsally around cerebral aqueduct and
decussate in superior medullary velum.
158
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
SECTION I Anatomy
• Emerges from dorsum of pons (only cranial nerve to
arise from dorsum of brainstem).
• Winds round cerebral peduncle.
• Passes forwards between superior cerebellar and posterior cerebral arteries to pierce dura.
• Runs forward on lateral wall of cavernous sinus between
oculomotor and ophthalmic nerves.
• Enters orbit through superior orbital ssure lateral to
tendinous ring from which recti take origin.
• Passes medially over optic nerve to enter superior
oblique muscle.
Clinical Point
• Injury to trochlear nerve results in paralysis of superior
oblique, resulting in diplopia when patient looks downwards and laterally. e patient complains of diculties
when walking downstairs.
V Trigeminal Nerve
e trigeminal nerve comprises three divisions:
• ophthalmic: sensory
• maxillary: sensory
• mandibular: mixed sensory and motor.
It is distributed as follows:
• sensory: to face, scalp, teeth, mouth, nasal cavity, paranasal sinuses and most of dura mater
• motor: to muscles of mastication, mylohyoid,
anterior belly of digastric, tensor tympani and tensor
palati
• ganglionic connections to the ciliary, sphenopalatine,
otic and submandibular ganglia.
e nuclei of the trigeminal nerve lie as follows:
• Motor nucleus:
• situated in upper part of pons near oor of fourth
ventricle.
• Sensory nuclei:
• mesencephalic nucleus (concerned with propriocep-
tion) is in the midbrain
• the chief sensory nucleus, concerned with touch,
tactile discrimination and position sense, lies in the
pons
• the nucleus of the spinal tract, concerned with
pain and temperature, is in the medulla and
extends caudally into the upper segments of the
spinal cord.
Trigeminal Ganglion
• Lies in invaginated pocket of dura in the middle cranial
fossa.
• Lies near apex of petrous temporal bone in a hollow
(Meckel’s cave).
• Motor root of nerve and greater supercial petrosal
nerve pass deep to ganglion.
• Hippocampal gyrus of temporal lobe lies above.
• Medially lies the internal carotid artery and part of the
cavernous sinus.
Ophthalmic Division
• Smallest division.
• Wholly sensory.
• Innervates skin of forehead, upper eyelid and most of nose.
• Passes forwards to enter lateral wall of cavernous sinus.
• Lies below trochlear nerve in cavernous sinus.
• Divides into three branches just before entering orbit:
1. Frontal:
• runs forwards beneath roof of orbit
• divides into supratrochlear and supraorbital nerves
supplying upper eyelid and scalp as far back as the
lambdoid suture.
2. Lacrimal:
• to lacrimal gland via postganglionic parasympathetic bres from pterygopalatine ganglion,
which it reaches via the maxillary nerve
• to the lateral part of the conjunctiva and upper eyelid.
3. Nasociliary:
• to ciliary ganglion
• eyeball
• cornea and conjunctiva of medial part of upper
eyelid
• dura of anterior cranial fossa
• mucosa and skin of nose.
Maxillary Division
• Wholly sensory.
• Passes forwards to leave skull through foramen rotundum.
• Emerges into pterygopalatine fossa.
• Continues through inferior orbital ssure and infraorbital canal, becoming the infraorbital nerve supplying
the skin of the cheek and lower eyelid.
• Branches:
• zygomatic, giving zygomaticotemporal and zygo-
maticofacial branches to the skin of the temple and
cheek, respectively
• superior alveolar branches to teeth of upper jaw
• branches from the pterygopalatine ganglion.
Pterygopalatine ganglion
• Lies in pterygopalatine fossa.
• Receives parasympathetic (secretomotor) root via the
greater supercial petrosal branch of cranial nerve VII;
sensory component from two pterygopalatine branches
of maxillary nerve; and sympathetics from the internal
carotid plexus.
CHAPTER 6 The Nervous System
159
• Parasympathetic eerents pass to lacrimal gland.
• Sensory and sympathetic bres to nose, nasopharynx,
palate and orbit.
Mandibular Division
• Largest division.
• Motor and sensory.
• Supplies:
1. Sensory:
• skin of temporal region
• part of auricle
• lower face
• mucous membrane of the anterior two-thirds of
the tongue and oor of the mouth.
2. Motor:
• muscles of mastication.
3. Parasympathetic:
• secretomotor to parotid gland.
• Passes forwards from trigeminal ganglion to enter foramen ovale.
• Gives o nervus spinosus to supply dura mater and nerve to
medial pterygoid, from which otic ganglion is suspended.
• Divides into small anterior and large posterior trunk.
• Anterior trunk:
• sensory branch, i.e. buccal nerve to skin of cheek and
mucous membrane of cheek
• motor to masseter, temporalis and lateral pterygoid.
• Posterior trunk:
• auriculotemporal nerve (sensory to temple and auri-
cle; secretomotor bres from otic ganglion to parotid
gland)
• lingual nerve:
• parasympathetic secretomotor bres from the
chorda tympani join the lingual nerve to supply
the submandibular gland
• terminal branches are distributed to the anterior
two-third of the tongue, the oor of the mouth
and the lingual surface of the gums
• inferior alveolar nerve:
• enters mandibular canal and supplies teeth of
lower jaw
• emerges through mental foramen, supplying skin
of chin and lower lip
• also supplies motor nerves, i.e. nerve to mylohyoid, supplying mylohyoid and anterior belly of
digastric.
Otic Ganglion
• Lies immediately below foramen ovale, lying close to the
medial surface of the mandibular nerve.
• Parasympathetic bres through the lesser supercial
petrosal branch of the glossopharyngeal nerve relay in
the ganglion, and pass via the auriculotemporal nerve
to the parotid as secretomotor supply.
• Sympathetic bres—from plexus on middle meningeal
artery—are vasoconstrictor.
• Sensory bres via auriculotemporal nerve to parotid gland.
• Motor bres (not present in any other cranial ganglion)
pass through the ganglion from the nerve to medial
pterygoid to supply tensor tympani and tensor palati.
Submandibular Ganglion
• Lies between hyoglossus and deep part of submandibular gland.
• Suspended from lower aspect of lingual nerve.
• Parasympathetic bres from chorda tympani of facial
nerve conveyed by lingual nerve carrying secretomotor
bres to sublingual and submandibular gland.
• Sympathetic bres from superior cervical ganglion via
plexus on facial artery supply vasoconstrictor bres to
sublingual and submandibular glands.
• Sensory component via lingual nerve to salivary glands
and mucous membrane of oor of mouth.
Clinical Points
• Division of the whole trigeminal nerve results in unilateral anaesthesia of the face and the anterior part of
the scalp, the auricle, and the mucous membranes of the
nose, mouth and anterior two-thirds of tongue. Paralysis
and wasting of the muscles of mastication occur on the
aected side.
• Pain is frequently referred from one segment to another.
A patient with a carcinoma of the tongue (lingual nerve)
may complain of earache (via the auriculotemporal
nerve). e classical description used to be the case of
an elderly man sitting in outpatients spitting blood with
a piece of cotton wool in his ear.
VI The Abducens Nerve
• Supplies lateral rectus.
• Nucleus in oor of fourth ventricle in upper part of pons.
• Fibres of facial nerve wind round nucleus to form facial
colliculus.
• Emerges between medulla and pons.
• Passes forwards through pontine cistern.
• Pierces dura mater to enter cavernous sinus lying on lateral aspect of internal carotid artery.
• Enters orbit through tendinous ring at superior orbital
ssure.
Clinical Points
• Has a long intracranial course and therefore frequently
involved in injuries to base of skull.
• Damage gives rise to diplopia and a convergent squint.
160
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
SECTION I Anatomy
VII Facial Nerve
• Supplies muscles of facial expression.
• Conveys parasympathetic bres to:
• lacrimal gland
• glands in nasal cavity
• submandibular salivary glands
• sublingual salivary glands.
• Transmits taste bres from anterior two-thirds of tongue.
• Motor nucleus in lower pons.
• Motor bres loop round abducens nerve nucleus (facial
colliculus) and emerge at cerebellopontine angle with
nervus intermedius (contain sensory and parasympathetic bres).
• Sensory bres synapse in nucleus of tractus solitarius in
the pons.
• Autonomic bres originate in the superior salivary
nucleus in the pons.
• Nervus intermedius lies lateral to motor bres of facial
nerve in between latter and vestibulocochlear nerve.
• Motor bres of facial nerve and nervus intermedius
pass through the pontine cistern and enter the internal
acoustic meatus, where the two join together to form
the facial nerve.
• Nerve then passes through facial canal in petrous temporal bone.
• Runs laterally over vestibule to reach medial wall of
middle ear, where it bends sharply backwards over the
promontory.
• is sharp bend, the genu, has the geniculate ganglion.
• Nerve passes downwards on posterior wall of middle
ear to emerge through the stylomastoid foramen at the
base of the skull.
• Branches given o in the petrous temporal bone are:
• greater petrosal nerve
• nerve to stapedius
• chorda tympani.
• Greater petrosal nerve transmits preganglionic parasympathetic bres to sphenopalatine ganglion, the
postganglionic bres supplying the lacrimal glands and
nasal cavity glands.
• Chorda tympani carries parasympathetic bres to submandibular and sublingual salivary glands and taste
bres from anterior two-thirds of tongue.
• Aer emerging from the stylomastoid foramen, the
nerve enters the parotid gland and divides into the following branches:
• temporal
• zygomatic
• buccal
• mandibular
• cervical.
• Testing of individual branches of the facial nerve is
important aer head and neck surgery, e.g. supercial
parotidectomy. e following tests may be carried out
to assess the various branches of the facial nerve:
• to test frontalis, ask patient to raise eyebrows.
Normally wrinkles are seen on the forehead. Tests
temporal branch
• to test orbicularis oculi, ask patient to close eyelids
tightly against resistance. Tests temporal and zygomatic branches
• to test levator anguli oris, ask patient to show teeth to
check that the angles of the mouth move equally on
both sides. Tests buccal branch
• to test orbicularis oris, ask patient to purse lips
tightly against resistance. Tests buccal and marginal
mandibular branch
• to test buccinators, ask patient to blow out the cheeks,
keeping the mouth shut. Tap the cheek to see if air
escapes from the closed mouth. Tests buccal branch
• to test risorius, ask patient to smile. e angle of the
mouth will not move on the side of the lesion. Tests
buccal nerve
• to test depressor anguli oris (draws the angle of
the mouth downwards and laterally), ask patient to
smile. e lower lip on the side of the lesion remains
elevated thus distorting the smile. Tests marginal
mandibular branch
• to test platysma, ask patient to clench the teeth and
simultaneously depress the angles of the mouth.
Normally, longitudinal folds of skin become obvious
in the neck when platysma contracts. Tests cervical
branch.
Clinical Points
• Infranuclear paralysis may be caused by malignant
tumours of the parotid, parotid surgery, acoustic neuroma and its surgery, and fracture of the base of the
skull.
• It is important to distinguish between a supranuclear
facial palsy and a nuclear or infranuclear facial palsy.
• Nuclear and infranuclear palsy aects all muscles on the
same side of the face.
• Supranuclear palsy aects contralateral facial muscles
but spares the frontalis and orbicularis oculi, since
the part of the facial nucleus supplying these muscles
receives bres from both cerebral hemispheres, i.e. there
is bilateral cortical representation. Supranuclear palsy is
likely to result from cerebrovascular accidents involving the corticobulbar pathways. If a patient with a right
cortical defect is asked to look up and smile, the patient
will be unable to raise the le side of the mouth but the
Соседние файлы в папке @xirurgi_2025