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By Dr. Fekry Shata Assistant prof. of anatomy & embryology Faculty of Dentistry Majmaa university FACIAL NERVE 7 TH CRANIAL NERVE

Mixed *Has two roots:- 1)-Motor :- facial nerve proper (large medial) 2)-Mixed:- nervus intermedius (small lateral) a. Parasympathetic. a. Parasympathetic. b. Sensory. b. Sensory.

Small lateral sensory root (nervus intermedius) Large medial motor root

M SSN N.S. S.T.N. Has 4 nuclei

1- Motor nucleus in pons 4-Spinal trigeminal nucleus 2- Superior salivary nucleus in pons 3-Nucleus soliterius in M.O. Facial nerve proper: purely motor. *all muscles of face, scalp except levator palpapri superiosis *All muscles derived from 2 nd pharyngeal arch Nervus intermedius:- parasympathetic: -through submandibular ganglion: to sublingual & submandibular salivary gland -through Sphenopalatine ganglion: to lacrimal gland Nervus intermedius:- Special sensation: Taste sensation from anterior 2/3 of tongue Nervus intermedius:- General sensation: external auditory meatus

Small lateral sensory root (nervus intermedius) Large medial motor root

Stylomastoidforamen

Stylomastoidforamen

1-Geniculate ganglion: gives rise to:- greater superficial gives rise to:- greater superficial petrosal n. petrosal n. 2- pterygopalatine g. 3- Submandibular g.

Geniculate ganglion Greater superficial petrosal nerve Vestibulocochlear nerve

G.S.P.N. D.P.N. Geniculate ganglion facial n. (7 th n.) Nerve to pterygoid canal (vidian nerve)

Mandibular nerve lingual nerve. facial n. (7 th n.) Chordatympani

1.Intracranial course 2.Intracanalicular course 3.Extracranial course 1.Intracranial course 2.Intracanalicular course 3.Extracranial course

1.Intracranial course (inside cranial cavity) Enter internal auditory meatus

Motor n. of facial PONS Motor n. of ABDUCENT Internal genu Facialcolliculus

PONS Internal auditory meatus 8 th cranial n.

2.Intracanalicular course (inside facial canal) (in middle ear)

PONS Internal auditory meatus 8 th cranial n. Geniculate ganglion Greater superficial petrosal nerve Facial canal

3.Extracranial course (in the face) enter the face by passing through stylomastoid foramen

Geniculate ganglion Facial canal Stylomastoidforamen

Stylomastoidforamen

Upper (temporofacial) division Lower (cervicofacial) division

Retromandibularvein E.C.A. Medial pterygoid Masseter Parotid gland Facial nerve

Upper (temporofacial) division Lower (cervicofacial) division PosteriorAuricularnerve Descending (n. to posterior Belly of Digastric)nerve Temporal branch Zygomatic branch Upper root of buccal Lower root of buccal Marginal (mandibular) branch Cervical branch

1 st part : no branches 2 nd part : (within middle ear or facial canal) 1- Greater superficial petrosal n. 1- Greater superficial petrosal n. 2- Tympanic 2- Tympanic 3- Chorda tympani 3- Chorda tympani 4- Nerve to stapedius 4- Nerve to stapedius 3- 3 rd PART : Gives 7 branches A. before entering parotid gland: A. before entering parotid gland: 1*post. Auricular n. 1*post. Auricular n. 2*n.to post. belly of digastric 2*n.to post. belly of digastric B. Terminal (after entering parotid gland): B. Terminal (after entering parotid gland): 1*Temporal 1*Temporal 2*Zygomatic 2*Zygomatic 3*Buccal 3*Buccal 4*Marginal(mandibular) 4*Marginal(mandibular) 5*Cervical 5*Cervical

Greater superficial petrosal nerve Origin: From geniculate ganglion. Origin: From geniculate ganglion. Its fibers arise from: superior salivarv nucleus. Its fibers arise from: superior salivarv nucleus. contains secretomotor parasympathetic fibers. contains secretomotor parasympathetic fibers. Course: Course: Runs towards the foramen lacerum.Runs towards the foramen lacerum. Termination: Termination: *At foramen lacerum joins deep petrosal nerve to form nerve of the pterygoid *At foramen lacerum joins deep petrosal nerve to form nerve of the pterygoid canal (Vidian nerve). canal (Vidian nerve). *In pterygopalatine fossa it joins the back of pterygopalatine ganglion. *In pterygopalatine fossa it joins the back of pterygopalatine ganglion. Branches & distribution: Branches & distribution: Taste fibers: to palate.Taste fibers: to palate. Preganglionic Parasympathetic fibers: to pterygopalatine ganglion.Preganglionic Parasympathetic fibers: to pterygopalatine ganglion.

G.S.P.N. D.P.N. Geniculate ganglion facial n. (7 th n.) Nerve to pterygoid canal (vidian nerve)

Tympanic branch Small branches to tympanic plexus to with the 9th nerve. Small branches to tympanic plexus to with the 9th nerve.

Chorda tympani Origin: from facial nerve in temporal bone, a short distance above stylomastoid foramen. Origin: from facial nerve in temporal bone, a short distance above stylomastoid foramen. Course: Course: -ascends in a bony canaliculus to the posterior wall of the middle ear. -passes forwards across the upper part of tympanic membrane. Termination: Termination: -joins lingual nerve (branch of mandibular nerve). Distribution: Distribution: 1.Taste fibers: anterior 2/3 of tongue. 2. Preganglionic parasympathetic fibers to:- (1)-submandibular salivary glands. (1)-submandibular salivary glands. (2)-subligual salivary glands. (2)-subligual salivary glands. (3)-glands in the anterior two thirds of tongue. (3)-glands in the anterior two thirds of tongue.

Choda tympani Squamotympanicfissure Lingual nerve

Mandibular nerve lingual nerve. facial n. (7 th n.) Chordatympani

Nerve to stapedius motor fiber to the stapedius muscle of the middle ear

Extracranial branches (in the face)

PosteriorAuricularnerve occipitalis Auricularis Descending (n. to posterior Belly of Digastric)nerve Temporal branch frontalis S A P Zygomaticbranch Upper root of buccal Lower root of buccal Marginal (mandibular) branch Cervical branch Orbecularisoculi platysma

1.LMNL *lesion in the facial nerve or in the facial n. *causes flaccid paralysis of all muscles of facial expression on the same side of the face. (Bell's palsy). (Bell's palsy).

Signs of the Lesion (same side of the face) A Paralysis of the frontalis muscle: inability to raise the eyebrow. B. Paralysis of the orbicularis oculi muscle: a. Inability to close the eye b. Loss of the corneal reflex. a. Inability to close the eye b. Loss of the corneal reflex. C. Paralysis of the orbicularis oris: inability to whistle. D. Paralysis of the levators of the angle of the mouth: drooping of the angle of the mouth. drooping of the angle of the mouth. E. Paralysis of the buccinator muscle: accumulation of food in vestibule of the mouth. accumulation of food in vestibule of the mouth. F. Paralysis of the stapedius muscle : hyperacusis (hypersensitivity to sounds). hyperacusis (hypersensitivity to sounds). G. Affection of the chorda tympani: a. loss of taste sensation from the anterior 2/3 of the tongue. a. loss of taste sensation from the anterior 2/3 of the tongue. b. decreased salivation. b. decreased salivation. H. Affection of the greater superficial petrosal nerve: loss of lacrimation loss of lacrimation

2. UMNL Due to: lesion in the corticobulbar fibers (above the level of nuclei). Due to: lesion in the corticobulbar fibers (above the level of nuclei). Leads to: Leads to: =paralysis of the lower half of the contralateral facial nucleus. =paralysis of the lower half of the contralateral facial nucleus. =paralysis of the muscles of the lower half of the opposite side of the face =paralysis of the muscles of the lower half of the opposite side of the face 1.inability to whistle, 1.inability to whistle, 2.drooping of the angle of the mouth. 2.drooping of the angle of the mouth. 3.accumulation of food in the vestibule of the mouth. 3.accumulation of food in the vestibule of the mouth.

Summary of para- sympathetic supply of H&N

E.W.N. MIDBRAIN I.S.N. M.O. C.G. S.P.G. S.C.S.G. Mandibular nerve S.M.G. Tympanic Plexus In Middle ear Mandibular nerve O.G. S.S.N. PONS

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