1. by dr. fekry shata assistant prof. of anatomy & embryology faculty of dentistry majmaa...

1

By

Dr. Fekry ShataAssistant prof. of anatomy & embryology

Faculty of Dentistry Majmaa university

FACIAL NERVE7TH CRANIAL NERVE

Mixed*Has two roots:-1)-Motor :- facial nerve proper (large medial)

2)-Mixed:- nervus intermedius (small lateral) a. Parasympathetic. b. Sensory.

Small lateral sensory root(nervus intermedius)

Large medial motor root

MSSN

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 2nd 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

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.(7th n.)

Nerve to pterygoid canal(vidian nerve)

Mandibular nerve

lingual nerve.

facial n.(7th n.)

Chordatympani

1.Intracranial course2.Intracanalicular course3.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 auditorymeatus

8th cranial n.

2.Intracanalicular course(inside facial canal)

(in middle ear)

PONS

Internal auditorymeatus

8th 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 ganglionFacial 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

PosteriorAuricular

nerve

Descending(n. to posterior

Belly ofDigastric)

nerve

Temporal branch

Zygomatic branch

Upper root of buccal

Lower root of buccal

Marginal (mandibular)branch

Cervical branch

1st part : no branches2nd part : (within middle ear or facial canal) 1- Greater superficial petrosal n. 2- Tympanic 3- Chorda tympani 4- Nerve to stapedius3- 3rd PART : Gives 7 branches A. before entering parotid gland: 1*post. Auricular n. 2*n.to post. belly of digastric B. Terminal (after entering parotid gland): 1*Temporal 2*Zygomatic 3*Buccal 4*Marginal(mandibular) 5*Cervical

Greater superficial petrosal nerve Origin: From geniculate ganglion.

Its fibers arise from: superior salivarv nucleus. contains secretomotor parasympathetic fibers.

Course: • Runs towards the foramen lacerum.

Termination: *At foramen lacerum joins deep petrosal nerve to form nerve of the

pterygoid canal (Vidian nerve). *In pterygopalatine fossa it joins the back of pterygopalatine ganglion.

Branches & distribution: • Taste fibers: to palate.• Preganglionic Parasympathetic fibers: to pterygopalatine ganglion.

G.S.P.N.

D.P.N.

Geniculate

ganglion

facial n.(7th n.)

Nerve to pterygoid canal(vidian nerve)

Tympanic branch

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.

Course: -ascends in a bony canaliculus to the posterior wall of the

middle ear. -passes forwards across the upper part of tympanic

membrane. Termination:-joins lingual nerve (branch of mandibular nerve).

Distribution: 1.Taste fibers: anterior 2/3 of tongue.2. Preganglionic parasympathetic fibers to:- (1)-submandibular salivary glands. (2)-subligual salivary glands. (3)-glands in the anterior two thirds of tongue.

Choda tympani

Squamotympanicfissure

Lingual nerve

Mandibular nerve

lingual nerve.

facial n.(7th n.)

Chordatympani

Nerve to stapedius

motor fiber tothe stapediusmuscle of themiddle ear

Extracranial branches(in the face)

PosteriorAuricular

nerve

occipitalis

Auricularis

Descending(n. to posterior

Belly ofDigastric)

nerve

Temporal branchfrontalis

SAP Zygomatic

branch

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).

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.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.E. Paralysis of the buccinator muscle:

accumulation of food in vestibule of the mouth.F. Paralysis of the stapedius muscle:

hyperacusis (hypersensitivity to sounds).G. Affection of the chorda tympani:

a. loss of taste sensation from the anterior 2/3 of the tongue . b. decreased salivation.

H. Affection of the greater superficial petrosal nerve:

loss of lacrimation

2 .UMNL

• Due to: lesion in the corticobulbar fibers (above the level of nuclei).

• Leads to: =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 1.inability to whistle, 2.drooping of the angle 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.

Mandibularnerve S.M.G.

TympanicPlexus

InMiddle

earMandibular

nerve O.G.

S.S.N.

PONS

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