Motor nerve supply of face.

Presented by Dr Rince Mohammed

Junior Resident

Dept. of OMFS G.D.C Kottayam

MOTOR NERVE SUPPLY OF FACE

INTRODUCTION• A motor nerve is a nerve that carries command information out of the CNS & toward

effectors (muscles or glands) that will execute the commands.

• Face has motor nerve supply from

Facial

Occulomotor

Trochlear

Abducent

Mandibular nerve of trigeminal

Hypoglossal nerve

Accessory

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FACIAL NERVE• Seventh cranial nerve

• Mixed nerve

• Nerve of 2nd branchial arch

• Emerges from the brainstem between the pons and the medulla

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EMBRYOLOGY

The facial nerve is derived from the hyoid arch.

The motor division is derived from the basal plate of the embryonic pons.

The sensory division originates from the cranial neural crest.

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NUCLEI• Motor nucleus

• Superior salivatory nucleus or parasympathetic

• Lacrimatory nucleus

• Nucleus of tractus solitarius

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• Motor nucleus lies deep in reticular formation of lower pons. Controls muscle activity.

• Muscles of upper part of face receives corticonuclear fibers from motor cortex of both right and left sides.

• Muscles of lower part of face receive corticonuclear fibers only from opposite cerebral hemisphere.

COURSE AND RELATIONS• The path of the facial nerve can be divided into

Intracranial

Intratemporal• Intrameatal• Labyrinthin• Tympanic• Mastoid

Extracranial

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Intracranial course:

• Facial nerve is attached to brainstem by two roots, motor and sensory.

• The motor part of the facial nerve arises from the facial nerve nucleus in the pons while the sensory and parasympathetic parts of the facial nerve arise from the intermediate nerve.

• Two roots are attached to lateral part of lower border of pons just medial to eighth cranial nerve.

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• From the brain stem, the motor and sensory parts of the facial nerve join together and traverse the posterior cranial fossa before entering the petrous temporal bone via the internal auditory meatus.

• Upon exiting the internal auditory meatus, the nerve then runs a tortuous course through the facial canal, which is divided into the labyrinthine, tympanic, and mastoid segments.

Overview of Facial Nerve anatomy in the skull

Lacerate foramen

Facial canal

Internal AcousticMeatus

StylomastoidForamen

Hiatus of canal of greater superficial petrosal nerve

Pterygoid canal

Greater superficialPetrosal nerve (GSPN)

Petrotympanicfissure

Greater andlesser palatinecanals

Chorda tympani nerve

Facial nerve

Facial nerve

PosteriorCranialFossa (PCF)

Inferior Orbital Fissure

The facial nerve exits the posterior cranial fossa (PCF) at the internal acoustic meatus.

Click here to start Animation

Posteriorauricular N.

O The labyrinthine segment is very short, and ends where the facial nerve forms a bend known as the geniculum of the facial nerve ("genu" meaning knee), which contains the geniculate ganglion for sensory nerve bodies.

O The first branch of the facial nerve, the greater superficial petrosal nerve, arises here from the geniculate ganglion.

O The greater petrosal nerve runs through the pterygoid canal and synapses at the pterygopalatine ganglion. Post synaptic fibers of the greater petrosal nerve innervate the lacrimal gland.

https://en.wikipedia.org/wiki/Geniculate_ganglion

https://en.wikipedia.org/wiki/Greater_petrosal_nerve




Lacerate foramen


StylomastoidForamen


Pterygoid canal




Chorda tympani

Facial nerve

Facial nerve

PosteriorCranialFossa



The first branch of the facial nerve, the greater superficial petrosal nerve (GSPN) branches from the geniculate ganglion within the genu of the facial canal and enters the middle cranial fossa (MCF) by way of the hiatus of the canal for the GSPN.

Geniculate ganglion

Facial canal

MCF


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal



Chorda tympani

Facial nerve

Facial nerve




The second branch of the facial nerve, the stapedial nerve, branches from the descending portion of the facial nerve and enters the middle ear.

Stapedial N. Petrotympanicfissure

Posteriorauricular N.


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal




Chorda tympani N.

Facial nerve

Facial nerve




The third branch of the facial nerve, the chorda tympani nerve, branches from the descending portion of the facial nerve and enters the middle ear. Within the middle ear the chorda tympani nerve crosses the medial surface of the tympanic membrane. It then passes through the petrotympanic fissure to enter the infratemporal fossa.

Infratemporalfossa


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal




Chorda tympani

Facial nerve

Facial nerve




The descending portion of the facial nerve exits the facial canal at the stylomastoid foramen and continues into the parotid region

ParotidregionPosterior

auricular N.

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Extracranial course:

• Facial nerve crosses lateral side of base of styloid process.

• Enters posteromedial surface of the parotid gland, runs forwards through the gland crossing the retromandibular vein and the external carotid artery.

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• Behind the neck of mandible it divides into its five terminal branches which emerge along the anterior border of the parotid gland.This is called as Pes anserinus (goose's foot) and it separates parotid into deep and superficial lobes.

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BRANCHES AND DISTRIBUTION

A. Within the facial canal: Greater petrosal nerve Nerve to the stapedius Chorda tympani

B. At its exit from the stylomastoid foramen:

Posterior auricular Digastric Stylohyoid

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C. Terminal branches within the parotid gland:

Temporal Zygomatic Buccal Marginal mandibular Cervical

D. Communicating branches with adjacent cranial and spinal nerves

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Greater petrosal nerve

Arises from geniculate ganglion of the facial nerve and innervate the lacrimal gland.

• Carries parasympathetic preganglionic fibers from the facial nerve and synapses with the pterygopalatine ganglion.

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Nerve to the stapedius

Arises opposite the pyramid of the middle ear.

Supplies the stapedius muscle.

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Chorda tympani

• Arises in the vertical part of the facial canal 6mm above the stylomastoid foramen.

• The fibers of the chorda tympani travel with the lingual nerve to the submandibular ganglion which go on to innervate the submandibular and sublingual salivary glands.

• Special sensory (taste) fibers also extend from the chorda tympani to the anterior 2/3 of the tongue via the lingual nerve.

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Posterior auricular nerve

Arises just below the stylomastoid foramen

Supplies auricularis posterior, occipitalbelly of occipitofrontalis and intrinsic muscles on the back of auricle

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Digastric branch Arises close to posterior auricular nerve

Supplies posterior belly of digastric

Stylohyoid branch

Arise with the digastric branch

Supplies stylohyoid muscle

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Temporal branches

• Cross the zygomatic arch

• Supply auricularis anterior, auricularis superior, intrinsic muscles on the lateral side of the ear, frontalis, orbicularis oculi, corrugator supercilli.

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Zygomatic branches

• Run across zygomatic bone

• Supply orbicularis oculi which close the eyelid.Paralysis lead to epiphora,prevents blinking.

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Buccal branches

• Two in number

• Upper branch runs above parotid duct

• Lower branch below the duct

• Supply to Buccinator,Muscles of nose and upper lip.Paralysis causes dribbling from the mouth.

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Marginal mandibular branch

• Runs below angle of mandible deep to platysma

• Crosses body of mandible and supplies muscles of lower lip and chin

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Cervical branch

• Emerge from the apex of the parotid gland, runs downwards and forwards in neck to supply Platysma.

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Communicating branches

• For effective coordination between the movements of the muscles of first, second and third branchial arches, facial nerve communicates with the sensory nerves distributed over its motor territory.

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FUNCTIONAL COMPONENTS• Special visceral efferent

• Muscles of facial expression

• Elevation of hyoid bone-digastric

General visceral efferent or parasympathetic Secretomotor to submandibular

Sublingual salivary glands

Lacrimal gland

Glands of nose, palate, pharynx

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• General visceral afferent• Afferent impulses from above mentioned glands

• Special visceral afferent• Taste sensations from ant 2/3 rd of tongue

• Palate

• General somatic afferent• Innervate part of skin of ear

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GANGLIA

• Geniculate ganglion

• Located on the first bend of the facial nerve

• Sensory ganglion

• The greater petrosal nerve,emerges from the anterior aspect of the ganglion

• Taste fibers present in nerve are peripheral processes of neurons present in this ganglion.

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Submandibular ganglion

Parasympathetic ganglion for relay of secretomotor fibers to the submandibular and sublingual glands

• Pterygopalatine ganglion

• Parasympathetic ganglion -lies in pterygopalatine fossa

• Secretomotor fibers meant for the lacrimal gland relay in this ganglion

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APPLIED SURGICAL ANATOMY• Damage is possible in severe maxillofacial injuries

with basilar skull fractures anywhere in the area of course of nerve resulting in ipsilateral paralysis of muscles of facial expression.

• Of concern to the surgeon is the close proximity of the main trunk of facial nerve where it exits the stylomastoid foramen and mandibular condyle.

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After exiting the stylomastoid foramen, the nerve enters the substance of parotid gland where it divides into its upper and lower divisions just posterior to the mandible.

The approximate distance from the lowest point of the external bony auditory meatus to the bifurcation of the facial nerve is 2.3 cm

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• Posterior to the parotid gland, the nerve is at least 2cm deep into the skin surface, from this point the two branches curve around the posterior mandible, where they form plexus between the parotid gland and the masseter muscle.

• The terminal branches of facial nerve then spread in a fan like fashion as five separate nerves

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Temporal branch

It exits the parotid gland anterior to superficial temporal artery

During an open approach to the TMJ, violation of this branch is possible Often,patient cannot squeeze the ipsilateral eye together or wrinkle the forehead. This inability is usually caused by retractor trauma or soft tissue edema. If this is the case, it should resolve itself during the first postoperative week.

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Zygomatic Branch

Its course is anterosuperior crossing the zygomatic bone

Inadvertent damage may occur to this nerve during open reduction of zygomatic arch or with the use of a zygomatic hook during closed approaches

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• Buccal Branch

• It runs almost horizontally and will often divide into separate branch above and below parotid duct as it runs anteriorly.

• Injury is possible in association with soft tissue trauma to the cheek region.

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• Marginal mandibular branch

• It run anteriorly parallel to inferior border of mandible

• It is usually encountered at the inferior border of the mandible just beneath the platysma muscle fibres during an open approach to the mandibular angle and body area.

• For this reason, an initial incision is made approximately 1 to 1.5cm below the inferior border which prevents trauma to the nerve.

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• Cervical Branch

• The cervical branch exits the parotid gland above its inferior pole and runs downwards underneath the platysma muscle.

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• The surgeon must be mindful of the facial nerves intimate involvement with the TMJ, specially when performing surgical approaches to the joint.

• The temporal and zygomatic branches are at increased risk during pre auricular approach and the marginal mandibular branch during submandibular approach.

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• The intra oral approach to the TMJ has minimal risk to the branches of facial nerve which is its major advantage.

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COMPLICATIONS OF PAROTID SURGERY

• Intra-operative or post-operative

• Post-operative complications can be classified as early and late complications.

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INTRA-OPERATIVE COMPLICATIONS

• Comprise transection of the facial nerve or one of its branches.

• In the event of nerve injury, immediate nerve repair is mandatory. Once the segments have been fully mobilized and brought together without tension, the two ends should be sutured together.

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• As an alternative to sutures, the surgeon may use fibrin tissue adhesive.

• If the nerve length is inadequate, a nerve graft of the greater auricular nerve, can be applied.

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POST-OPERATIVE COMPLICATIONS

• Post-operative facial nerve dysfunction is the most frequent early complication of parotid gland surgery.

• Temporary facial nerve paresis, involving all or just one or two branches of the facial nerve, and permanent total paralysis can occur.

• The cases of transient facial nerve paresis generally resolve within 6 months.

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• The incidence of facial nerve paralysis is higher with total parotidectomy, which may be related to stretch injury.

• The branch of the facial nerve most at risk for injury during parotidectomy is the marginal mandibular branch.

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• If facial paresis causes incomplete closure of the eye, the patient must be advised to use ophthalmic moisture drops frequently during the day and an ophthalmic ointment and eye protection at night.

• Regular follow-up with an ophthalmologist is mandatory.

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IDENTIFICATION OF FACIAL NERVE

3 surgical maneuvers used to identify nerve trunk

• Blood free plane in front of external acoustic meatus

• Exposure of anterior border of SCM before insertion into mastoid process

• Peripheral identification of terminal branch of facial nerve (marginal mandibular branch)

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LESIONS OF FACIAL NERVE

• Supra nuclear type (UMN)lesion

• Paralysis of lower part of face (opposite side)

• Partial paralysis of upper part of face

• Normal taste and saliva secretion

• Stapedius not paralysed

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Nuclear type

• A lesion in the pons may involve motor nucleus of facial nerve along with the abducent nerve.

• Whole paralysis of facial muscle (same side

• Eye cannot be closed.

• Paralysis of lateral rectus

• Internal strabismus

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Peripheral lesion

At internal acoustic meatus

• Paralysis of secretomotor fibers• Hyper acusis • Loss of corneal reflex• Taste fibers unaffected • Facial expression and movements

paralysed

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Injury distal to geniculate ganglion

• Complete motor paralysis (same side)

• Lacrymation preserved

• hyper acusis

• Loss of corneal reflex

• Taste fibers affected

• Facial expression and movements paralyzed

Bell's Palsy

• Commonest cause of acute VII paralysis

• Diagnosis of exclusion

• Unilateral facial paralysis

• Sudden onset

• Unknown cause

• LMNL

• Limited duration

• Spontaneous recovery

• No sensory loss

• Inability to smile, close eye or raise eyebrow

• Whistling impossible

• Drooping of corner of the mouth

• Inability to close eyelid (Bell’s sign)

• Inability to wrinkle forehead

• Loss of blinking reflex

• Slurred speech

• Mask like appearance of face

• Loss/ alteration of taste

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SYNDROMES ASSOCIATED WITH FACIAL NERVE

• Ramsay Hunt syndrome

• Moebius syndrome

• Cardiofacial syndrome

• Treacher collins syndrome

• Goldenhars syndrome

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RAMSAY HUNT SYNDROME• Herpes zoster infection of

geniculate ganglion

• Facial nerve paralysis

• Pain in external auditory meatus & pinna of ear

• Vesicular eruptions in oral cavity & oropharynx

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MOEBIUS SYNDROME• Abnormal VI ,VII,XII Nerve nuclei• Facial Nerve absent / smaller• Congenital Extra ocular muscle & facial

palsy

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CARDIOFACIAL SYNDROME• Unilateral facial paralysis involving only the

lower lip and congenital heart disease

• The paralysis is only recognizable when the patient talks, smiles or cries

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GOLDENHARS SYNDROME• Hemi facial microsomia

• Vertebral anomalies

• Congenital facial nerve palsy

Presented by Dr Rince Mohammed

Junior Resident

Dept. of OMFS G.D.C Kottayam

MOTOR NERVE SUPPLY OF FACE PART II

CONTENTS

Occulomotor nerveTrochlear nerveAbducent nerveMandibular nerve of trigeminalHypoglossal nerve

OCCULOMOTOR NERVE• 3rd cranial nerve

• Entirely motor

• Supplies Levator palpabrae superioris and all extrinsic muscle of eye except lateral rectus and superior oblique.

• Also innervates sphincter pupillae and cilliary muscle

Functional components

1. General Somatic efferent – Supplies 4 of the 6 extraocular muscles of the eye and the levator palpebrae superioris muscle.

2. General visceral efferent – Parasympathetic innervation of the constrictor pupillae and ciliary muscles.

3. General somatic afferent – proprioception from eyeball muscles-but relayed to trigeminal nuclei.

NUCLEUS

• Lies ventral to the grey matter around the cerebral aqueduct, at the level of superior colliculus.

• Consists of :

1. Main oculomotor nucleus

2. Edinger – westphal or accessory oculomotor nucleus

Occulomotor nuclei

• One centrally placed caudal nucleus supplies to both LPS.

• 4 lateral paired subnuclei that innervate

Superior rectus(paramedial),

Inferior rectus(dorsolateral),

Inferior oblique(intermedial).

Medial rectus(ventromedial)

Edinger-Westphal nucleus

Unpaired,parasympathetic-lies dorsal to motor nucleus

COURSE

Can be divided into –

• Fascicular (Intraneural)- fibers arise from nucleus and pass ventrally

• Basilar-At the base of the brain the nerve is attached to the occulomotor sulcus on the medial surface of crus cerebri. Nerve descends anteriorly in interpeduncular fossa between post. Cerebral and sup. Cerebellar arteries. It pierce the dura to reach the cavernous sinus.

• Intracavernous

• Intraorbital

INTRACAVERNOUS

• It traverse the post. Part of roof of the cavernous sinus to reach its lateral wall

• In the wall trochlear nerve and 1st & 2nd divisions of trigeminal nerve are inferolateral to it.

• Abducent nerve and internal carotid artery are Inferomedial.

• At the anterior part of sinus nerve divides into a small superior and larger inferior branch.

• These two divisions of nerve enter the orbit through middle part of sup. Orbital fissure(in annulus of zinn).

INTRAORBITAL

Two divisions:• Superior division: diverges medially above the optic nerve and

behind the nasocilliary nerve.Supplys to contralateral sup. rectus and levator palpebrae superioris muscles bilaterally.

Inferior division:

• Divides immediately into branches to supply- ipsilateral medial rectus, inferior rectus and inferior oblique muscle.

• Nerve to inf. Oblique enters the muscle as 2-3 branches, it also supplies to cilliary ganglion.

CILLIARY GANGLION

• Peripheral parasympathetic ganglion,lies near the apex of orbit between the optic nerve and the tendon of the lateral rectus muscle.

• Has 3 roots:

• Sympathetic root is a branch from int. carotid plexus.

• Sensory root-comes from nasocilliary nerve

• Parasympathetic root (motor root)-arise from nerve to inf. Oblique muscle.

Motor root contains preganglionic axons from the Edinger-Westphal nucleus.The postganglionic axons innervate two eye muscles:

• The sphincter pupillae-constricts the pupil.

• The ciliaris - contracts, making the lens more convex,known as accommodation

FUNCTIONS

• Elevation of eye lid (Levator palpabrae superioris)

• All movements of eye, except lateral, down and out movements.

• Miosis,accomodation and light reflex (Parasymp innervation)

OCULOMOTOR PALSY

can arise due to:

• direct trauma• demyelinating diseases (e.g., multiple sclerosis)• increased intracranial pressure• due to a space-occupying lesion (e.g., brain cancer)• subarachnoid haemorrhage (e.g., berry aneurysm)• microvascular disease, e.g., diabetes, Hypertension

CLINICAL FEATURES

• Drooping of eyelid

• Binocular double vision

• Pain (may be present)• Abduction of globe-leteral squint• Intortion of the globe which increases on attempted down

gaze• Limitation of adduction• Limitation of elevation• Limitation of depression• Dilated pupil with defective accommodation

TROCHLEAR NERVE

• 4th cranial nerve.Purely motor-Supplys to sup.Oblique muscle.

• The nerve is named for the trochlea, the fibrous pulley through which the tendon of the superior oblique muscle passes.

• It is most slender, smallest nerve and has longest intra cranial course(7.5cm) of all cranial nerves.

• It is Only cranial nerve to emerge from dorsal aspect of brain.

• The only cranial nerve to cross completely on the other side i.e the trochlear nerve arises from the contralateral nucleus

FUNCTIONAL COMPONENTS

1. Somatic efferent – concerned with the movement of eyeball.

2. General somatic afferent – carries proprioceptive impulses from S.O. muscle to the mesencephalic nucleus of trigeminal nerve.

NUCLEUS

• Trochlear nucleus situated At the level of sup. border of inferior colliculus.

• Continous with 3rd nerve nucleus superiorly.

• From each nucleus nerve fibres first run laterally to mesencephalic nucleus of 5 th nerve, then somewhat downwards and parallel to aqueduct

• At lower border of inf. Colliculus they turn medially to decussate in superior medullary velum,then it emerges on the dorsal aspect of sup. Cerebellar peduncle, Passes b/w post. Cerebral & sup. Cerebellar arteries and enters in cavernous sinus on post. Part of its roof and goes to its lateral wall.

COURSE

• The nerve enter in to orbit through superior orbital fissure and fans out into 3-4 branches to supply sup. Oblique muscle on its sup. Surface.

FUNCTION

• Sup. Oblique muscle Primarily rotates the tip of the eye towards the nose (Intorsion)

• Secondarily moves the eye downwards (depression)

• Tertiary function is to moves the eye outwards ( abduction)

• Trochlear nerve typically allows a person to view the tip of his or her nose.

Trochlear Nerve Palsy

• Congenital, or acquired

Clinical features• The involved eye is higher as a result of the weakness of the

superior oblique muscle. • Ocular Movements- Depression and Intorsion are limited.• Diplopia-The patient especially notices diplopia when coming

down the stairs.• Abnormal Head Posture-To avoid diplopia, the head takes an

abnormal head posture

ABDUCENT NERVE

ABDUCENT• Sixth cranial nerve Entirely motor , supplys to lateral rectus

muscle.

• Most vulnerable cranial nerve, to damage in traumas involving cranium.

FUNCTIONAL COMPONENT

1. Somatic efferent – for lateral movement of eye.

2. General somatic afferent : for proprioceptive impulses which are carried to mesencephalic nucleus of 5 th nerve.

NUCLEUS

• Abducent nucleus is Small mass of large multipolar cells, in floor of fourth ventricle, ventral to colliculus fascialis. where it is closely related to the horizontal gaze centre(PPRF).

• Fasciculus of the 7th nerve curves around the abducent nucleus.

• Efferent fibre starts from nucleus, traverse through tegmentum, Parapontine reticular formation(pprf) and pyramidal tract .

• Then leave the brainstem at pontomedullary junction.

• Lateral to each abducent there is the emergence of facial nerve. B/w two Abducent nerves there is basilar artery at its formation.

COURSE

• Nerve passes around inf.Petrosal sinus in anterolateral direction,under the petroclinoid ligament, to enter in cavernous sinus.then enters the orbit through superior orbital fissure.

CLINICAL FEATURES OF 6TH NERVE PALSY

1. Deviation- In primary position,eyeball is converged due to unopposed action of medial rectus muscle.

2. Ocular movements- Abduction is limited due to weakness of the lateral rectus muscle.

3. Diplopia- Uncrossed diplopia occurs, which becomes worse toward the action of paralysed muscle.

4. Head Posture- The face is turned towards the action of paralysed muscle to minimise diplopia.

MANDIBULAR NERVE

• 3rd and Largest division of trigeminal nerve

• Has both sensory and motor fibers

• Nerve of first branchial arch

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COURSE AND RELATIONS

• Begins in the middle cranial fossa through sensory and motor root.

• Sensory root arises from lateral part of trigeminal ganglion and leaves cranial cavity through the foramen ovale.

• Motor root lies deep to trigeminal ganglion,Passes through foramen ovale to join sensory root just below the foramen forming the main trunk.

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• Largest division of trigeminal nerve

• Nerve of first branchial arch

• Has both sensory and motor fibers

• The sensory root originates from trigeminal ganglion whereas the motor root originates in the pons and medulla

• The 2 roots emerge from the cranium separately through the foramen ovale, the motor root lying medial to sensory and they unite just outside the skull and form the main trunk.

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• Main trunk lies in the infratemporal fossa, deep to lateral pterygoid.

• After a short course, the main trunk divides into a small anterior trunk and a large posterior trunk.

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BRANCHES

• From the main trunk• Meningeal branch

• Nerve to medial pterygoid

• From the anterior trunk• Buccal nerve

• Masseteric nerve

• Deep temporal nerves

• Nerve to lateral pterygoid

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• From the posterior trunk• Auriculotemporal nerve

• Lingual nerve

• Inferior alveolar nerve

• Mylohyoid nerve

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Meningeal branch or Nervus Spinosus

• It re-enters the cranium through the foramen spinosum along with the middle meningeal artery.

• Supplies dura mater of middle cranial fossa

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Nerve to Medial Pterygoid

• Arises close to otic ganglion

• Supplies medial pterygoid, Tensor veli palatini, and the Tensor tympani muscles

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Buccal Nerve

• Only sensory branch of anterior division of mandibular nerve.

• Passes between the two heads of lateral pterygoid, runs downwards and forwards.

• Supplies skin and mucous membrane related to buccinator and labial aspect of gums of molar and premolars.

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Masseteric Nerve

• Emerges at upper border of lateral pterygoid in front of TMJ

• Passes laterally through mandibular notch along with masseteric vessels

• Supplies masseter and TMJ

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Deep temporal Nerves

• Two in number Anterior and posterior.

• They pass between the skull and the lateral pterygoid, and enters the deep surface of the temporalis.

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Nerve to Lateral Pterygoid

• It may be an independent branch or may arise in common with the buccal nerve

• Supply lateral pterygoid

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Auriculotemporal Nerve

• Arises by two roots, encircle middle meningeal artery, and unite to form a single trunk.

• Run backwards between neck of mandible and sphenomandibular ligament

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• Auricular part supplies skin of tragus, upper parts of pinna, external acoustic meatus and tympanic membrane.

• Temporal part supplies skin of temple

• Also supplies parotid gland and TMJ joint.

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Lingual Nerve

• Sensory to anterior 2/3rd of tongue and floor of mouth,lingual gingiva

• Also carries postganglionic fibres from submandibular ganglion to sublingual and anterior lingual glands

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Course and relations

• Begins 1 cm below skull, runs first between tensor veli palatini and lateral pterygoid, then between lateral and medial pterygoids.

• 2 cm below the skull it is joined by chorda tympani nerve.

• Runs downwards and forwards between ramus of mandible and medial pterygoid.

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• Next it lies in direct contact with mandible, medial to third molar.

• It soon leaves the gum and runs over hyoglossus.

• Finally, it lies on surface of genioglossus, winds round submandibular duct and divides into its terminal branches.

Applied Anatomy

Lingual nerve is at great risk during surgical removal of impacted third molar

During removal of submandibular salivary gland,during which the duct must be dissected from lingual nerve.

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Mylohyoid Nerve

• Arises just before the inferior alveolar nerve enters the mandibular foramen.

• It pierces the sphenomandibular ligament and enters a shallow groove on medial surface of mandible

• Supplies mylohyoid muscle and the anterior belly of digastric.

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Inferior Alveolar Nerve

• Largest branch of the mandibular division

• Runs downwards lateral to medial pterygoid and sphenomandibular ligament.

• Enters mandibular foramen and runs in the mandibular canal.

• It divides into mental and incisive branches.

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• Mental nerve-Emerges at mental foramen and supplies skin of chin, and the skin and mucous membrane of lower lip.

• Incisive branch supplies to: premolar

canineincisorsassociated labial gingiva

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CLINICAL ANATOMY

• Motor part of mandibular nerve is tested clinically by asking the patient to clench his teeth and then feeling for contracting masseter and temporalis muscles on the two sides.

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• If one masseter is paralysed, the jaw deviates to the paralysed side on mouth opening.

• The activity of pterygoid muscles is tested by asking the patient to move the chin from side to side.

HYPOGLOSSAL NERVE

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HYPOGLOSSAL NERVE

• Twelfth cranial nerve,purely motor

• Supplies the muscles of tongue

• It is called hypoglossal because it is seen below the tongue.

• The nerve arises from the hypoglossal nucleus.

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COURSE AND RELATIONS

• After exiting the brain, hypoglossal nerve passes through hypoglossal canal and winds around vagus nerve inferiorly.

• Then runs inferiorly across medial aspect of stylohyoid and digastric muscles.

• Then curves upward across internal and external carotid arteries and occipital and lingual arteries on their lateral side.

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• Runs forward along the lateral surface of hyoglossus muscle.

• At the posterior extent of mylohyoid muscle, the nerve runs along superomedial surface to split into several fibers into the surface of tongue.

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CLINICAL ANATOMY

• Hypoglossal nerve is tested by asking patient to protrude his tongue. If the nerve is paralysed, tongue deviates to paralysed side.

• Lesion of hypoglossal nerve produces paralysis of tongue on that side.

REFERENCES

• Gray's Anatomy - 40th Ed

• Human anatomy –B.D Chaurasia Volume 3

• Oral and maxillofacial trauma –Fonseca 4 th edition

• Textbook of Oral and Maxillofacial Surgery -Neelima Anil Malik

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Thank You…

Motor nerve supply of face.

Health & Medicine

Transcript of Motor nerve supply of face.