COURSE: ADVANCED ANATOMY II NEUROANATOMY

FACIAL NERVE TOPIC,. INTRODUCTION

EMBRYOLOGY OF FACIAL NERVE

NUCLEI OF FACIAL NERVE

FUNCTIONAL COMPONENTS

COURSE OF FACIAL NERVE

BRANCHES OF FACIAL NERVE

GANGLIA ASSOCIATES WITH FACIAL NERVE

FUNCTIONS OF FACIAL NERVE

BLOOD SUPPLY OF FACIAL NERVE

CLINICAL CORRELATION

REFERENCES
7th cranial nerve.
Nerve of second branchial arch
Mixed nerve carrying both motor and sensory fibres.
it is paired nucleus found on both sides .
During 3rdweek,the facioacoustic primordium develops,and gives rise to facial nerve
-4th week , facial nerve splits into two: chorda tympani and caudal main trunk.
-5th week geniculate ganglion and nervus intermedius develop.
-10 to 15th week Peripheral segment of facial nerve undergoes extensive branching .
The nerve is not fully developed until about 4 years of age

Motor nucleus
.To muscles of facial expression

2. Parasympathetic nulceus .
.Superior salivatory and lacrimatory nuclei
-Submandibualr and sublingular glands
-Lacrminal,nasal and palatine
3.Sensory nuclei
Nucleus of tractus solitarius-taste
Spinal nucleus of Trigeminal nerve
.Sensory root (NERVOUS INTERMEDIUS)
1-Superior salivatory nucleus
2.-Nulceus of solitarius
3.-Spinal trigeminal nucleus and tract

.Motor root
1.-Motor nucleus
1.Special visceral efferent fibres (SVE)
-Begin from the motor nucleus at the level of lower pons and supply the muscles of facial expression
-Posterior belly of digastric
-Platysma
-Stapedius muscle
2.General visceral efferent fibres .(GVE)
-These are preganglionic parasympathetic fibres which arise from lacrimatory and superior salivatory nuclei in the brainstem.
They supply the secretomotor fibres to lacrimal,
submandibular,
and sublingual glands
3. Special visceral afferent fibres(SVA)
.They carry special
sensations of taste from anterior two-third(2/3) of the tongue except vallate papillae and terminate in the Nucleus of
tractus solitarius (gustatory nucleus) in the brainstem.
General somatic afferent(GSA)
They carry general sensations from the skin of the auricle and terminate in the spinal nucleus of the trigeminal nerve.
Anatomically, the course of facial nerve is divided into two parts:
1-Intracranial: EXIT FROM THE BRAIN
2-Extracranial:EXIT FROM THE CRANIAL CAVITY
The nerve arises in the pons of the brainstem as two roots large Motor root and small Sensory root.
The roots leaves the internal acoustic meautus and enter the facial canal. The canal is “Z” shaped
two roots fuse to form facial nerve.
nerve forms the geniculate ganglion.
Nerve gives rise to
-Greater petrosal nerve
-Nerve to stapedius
-Chorda tympani
The facial nerve then exits the facial canal (and the cranium) via stylomastoid foramen.1st extracranial branch to rise is the posterior auricular nerve.
Distal to this are Nerve to digastric and Nerve to stylohyoid
The main trunk of the nerve, motor root of facial nerve, continues anteriorly and inferiorly into the parotid gland, to give five branches
Temporal

1. COURSE: ADVANCED ANATOMY II NEUROANATOMY CRANIAL NERVE 7/FACIAL NERVE DR KESHENI LEMI

2. OUTLINE . INTRODUCTION EMBRYOLOGY OF FACIAL NERVE NUCLEI OF FACIAL NERVE FUNCTIONAL COMPONENTS COURSE OF FACIAL NERVE BRANCHES OF FACIAL NERVE GANGLIA ASSOCIATES WITH FACIAL NERVE FUNCTIONS OF FACIAL NERVE BLOOD SUPPLY OF FACIAL NERVE CLINICAL CORRELATION REFERENCES

3. FACIAL NERVE : I N TRODUCTION 7 th cranial nerve. Nerve of second branchial arch Mixed nerve carrying both motor and sensory fibres. it is paired nucleus found on both sides .

4. Embryology facial nerve During 3 rd week,the facioacoustic primordium develops ,and gives rise to facial nerve -4 th week , facial nerve splits into two: chorda tympani and caudal main trunk. -5 th week geniculate ganglion and nervus intermedius develop. -10 to 15 th week Peripheral segment of facial nerve undergoes extensive branching . The nerve is not fully developed until about 4 years of age

5. Nuclei of Facial Nerve 1. Motor nucleus . T o muscles of facial expression 2 . Parasympathetic nulceus . .Superior salivatory and lacrimatory nuclei -Submandibualr and sublingular glands -Lacrminal,nasal and palatine

6. Nuclei of Facial Nerve 3.Sensory nuclei Nucleus of tractus solitarius-taste Spinal nucleus of Trigeminal nerve

7. ROOTS OF FACIAL NERVE .Sensory root (NERVOUS INTERMEDIUS) 1-Superior salivatory nucleus 2.-Nulceus of solitarius 3.-Spinal trigeminal nucleus and tract .Motor root 1.-Motor nucleus

8. Functional Components and Nuclei 1. Special visceral efferent fibres (SVE ) -Begin from the motor nucleus at the level of lower pons and supply the muscles of facial expression - Posterior belly of digastric -Platysma -Stapedius muscle

9. Functional Components and Nuclei 2 . General visceral efferent fibres .(GVE) - These are preganglionic parasympathetic fibres which arise from lacrimatory and superior salivatory nuclei in the brainstem. They supply the secretomotor fibres to lacrimal, submandibular, and sublingual glands

10. Functional Components and Nuclei 3. Special visceral afferent fibres(SVA) .They carry special sensations of taste from anterior two-third(2/3) of the tongue except vallate papillae and terminate in the Nucleus of tractus solitarius ( gustatory nucleus ) in the brainstem.

11. Functional Components and Nucle General somatic afferent(GSA) They carry general sensations from the skin of the auricle and terminate in the spinal nucleus of the trigeminal nerve.

12. Anatomically, the course of facial nerve is divided into two parts: 1-Intracranial: EXIT FROM THE BRAIN 2-Extracranial:EXIT FROM THE CRANIAL CAVITY ANATOMICAL COURSE OF FACIAL NERVE

13. INTRACRANIAL The nerve arises in the pons of the brainstem as two roots large Motor root and small Sensory root. The roots leaves the internal acoustic meautus and enter the facial canal. The canal is “Z” shaped two roots fuse to form facial nerve.

14. INTRACRANIAL nerve forms the geniculate ganglion. Nerve gives rise to - Greater petrosal nerve - Nerve to stapedius - Chorda tympani The facial nerve then exits the facial canal (and the cranium) via stylomastoid foramen.

15. EXTRACRANIAL 1 st extracranial branch to rise is the posterior auricular nerve . Distal to this are Nerve to digastric and Nerve to stylohyoid The main trunk of the nerve , motor root of facial nerve, continues anteriorly and inferiorly into the parotid gland , to give five branches Temporal branch Zygomatic branch buccal branch marginal mandibular branch cervical branch

16. BRANCHES OF FACIAL NERVE I N FACIAL CANAL 1- Greater superficial petrosal nerve Parasympathetic fibres to mucous glands and lacrimal gland 2- Nerve to stapedius - Motor fibres to stapedius muscles of the middle ear 3 -Chorda tympani Special sensory fibres to the anterior 2/3 tongue and parasympathetic fibres to the submandibular and sublingual glands

17. BRANCHES OF FACIAL NERVE AT STYLOMASTOID FORAMEN ( THREE MOTOR BRANCHES) 1- Posterior Auricular nerve innervates the intrinsic and extrinsic muscles of the outer ear. .s upplies the occipital part of the occipitofrontalis muscle. 2-Nerve to posterior belly of digastric - it is responsible for raising the hyoid bone. 3- S tylohyoid -innervates the stylohyoid muscle.

18. BRANCHES OF FACIAL NERVE 5 Terminal branches in the face 1.Temporal - innervates frontalis, orbicularis oculi and corrugator 2.Zygomatic- innervates the orbicularis oculi 3.Buccal- innervates the orbicularis oris ,buccinator and zygomaticus. 4.Marginal mandibular - innervates the depressor labii inferioris, depressor anguli oris and mentalis. 5.Cervical-I nnervates the platysma. These branches are responsible for innervating the muscles of facial expression.

19. PARASYMPATHETIC FIBERS SUBMANDIBULAR AND SUBLINGURAL GLANDS . Superior salivatory nulei >facial nerve/ greater petrosal nerve > chorda tympani >lingual nerve >submandibular ganglion >S ubmandibular and Sublingual salivary glands

20. PARASYMPATHETC FIBERS TO LACRIMAL GLANDS . L acrimal glands .Superior salivatory nulei > facial nerve/greater petrosal nerve >join deep petrosal nerve - nerve of petrygoid canal > Pterygo(sphenoidpalatine)palatine ganglion > maxillary nerve > zygomatic nerve > zygomasticotemporal nerve --Lacrimal nerve - lacrimal gland.

21. GANGLIONS ASSOCIATED WITH FACIAL NERVE . GENICULATE GANGLION . Located on the first bend of the facial nerve,in relation to the medial wall of middle ear. it is sensory ganglion. SUBMANDIBULAR GANGILION A parasympathetic ganglion for relay of secretomotor fibers to the submandibular and sublingual salivary glands. . Is the motor/parasympathetic fibers pass from the lingual nerve to the ganglion through the posterior root.

22. PTERYGO PLATINE GANGLION(SPHENOPALATINE GANGLION) Is the largest parasympathetic peripheral ganglion. It serves as a relay station for secretomotor fibers to the lacrimal gland and to the mucous glands of the nose, paranasal sinuses, palate and the pharynx. It is also called hay fever ganglion.

23. SUMMARY

24. BLOOD SUPPLY The facial nerve gets its blood supply from 4 vessels: Anterior inferior cerebellar artery - at the cerebellopontine angle Labyrinthine artrery (branch of anterior inferior cerebellar artery) – within internal acoustic meatus Superficial petrosal artery (branch of middle meningeal artery) – geniculate ganglion and nearby parts Stylomastoid artery . Venous drainage is into venae comitantes of the superficial petrosal and stylomastoid.

25. FUNCTIONS OF FACIAL NERVE . Contraction of the muscles of the face. . Production of tears from a gland.(lacrimal gland) . Conveying the sense of taste from the anterior 2/3 of the tongue (via the chorda tympani nerve) . The sense of touch at the auricular conchae.

26. 1. PARAYLSIS OF FACIAL NERVE . Paralysis of the facial nerve is fairly common. this involve Lower Motor Neuron (LMN) type of paralysis. and (Upper Motor Neuron type of paralysis) .Supranuclear facial paralysi s/ Upper motor neuron lesion/ - involve lesion in the corticobulbal tract. - hemiplegia of the lower part of the face .Infranuclear paralysis / Lower motor neuron lesion -involve lesion in the nerve -paralysis of all facial muscles on the same side. CLINICAL CORRELATION

27. Lower motor neuron lesion of facial nerve S. No. Site of lesion Effect A Stylomastoid foramen Ipsilateral loss of movement of all facial muscles (Bell’s palsy) B Geniculate ganglion As in A + hyperacusis, decreased taste from anterior two-thirds of the tongue, decreased salivary secretion, decreased lacrimation C Internal acoustic meatus/ cerebellopontine angle As in B + involvement of vestibulocochlear nerve which will result in deafness and loss of equilibrium D Facial nucleus (nuclear paralysis) As in B

28. Differences between supranuclear lesion(UMNL) and infranuclear lesion of facial nerve(LMNL) No. Supranuclear lesion of facial nerve(UMNL) Infranuclear lesion of facial nerve( LMNL) 1 Lesion is usually in internal capsule Lesion is usually at stylomastoid foramen 2 Accompanied by hemiplegia, on the same side as facial paralysis Hemiplegia, seen only in nuclear paralysis in lower pons, will be contralateral 3 Movements of the lower part of the face affected because the upper part of the face is under bilateral cortical control Movements of the entire half of face affected. 4 Voluntary movements are affected, emotional expressions appear to be normal since different pathways are involved Both voluntary and emotional movements are affected since it is final common pathway

29. Bell’s palsy happens when there’s inflammation and swelling of the seventh cranial nerve — the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bell’s palsy have no clear cause (idiopathic) . BELL’PALSY

30. 2.Crocodile tears syndrome It results in the facial nerve lesion proximal to the geniculate ganglion because regenerating preganglionic fibres to provide secretomotor supply to the submandibular and sublingular salivary glands during regeneration. It is a clinical condition characterized by paroxysmal lacrimation during eating.

31. It occurs due to the involvement of geniculate ganglion i n herpes zoster infection. Clinically, it presents with the following signs and symptoms: -herpetic vesicles of auricle -loss of lacrimation -hyperacusis -loss of sensation in anterior two third of tongue. -complete ipslilatera facial palsy (bells palsy) CLINICAL CORRELATION 3. Ramsay Hunt syndrome:

32. Mobius syndrome: partial or complete facial paralysis (mask like appearance,failure to close the eyes during sleeping) CLINICAL CORRELATION 4.Mobius syndrome

33. REFERENCE 1.Professor Anyanwu G Emeka. PAALS ANATOMY ,WWW.YOUTUBE/@PAALSANATOMY490 3 ,November 10 ,2022. 2. Richa . rd, S. Snell. 7th Edition . Clinical Neuroanatomy . Library Of Congress Cataloging-in-publication Data, Philadephia , 2010. 3. Kulkarni Neeta . Clinical Anatomy , A Problem Solving Approach . 2nd Ed. Jaypee Brothers Medical Publishers (P) Ltd. New Delhi. 2012. 4.Bhuiyan , Pritta S, Et Al (Editors). Inderbir Sing’s Textbook Of Human Neuroanatomy, Fundamental And Clinical. New Delhi. The Health Sciences Publisher. 2018. 5. Vishram Singh, T ext book of anatomy Head , N eck AND B rain , Volume III , Second Edition 2014. 6.Dr.Adel bondok,facialnerve lecture , https://youtu.be/DXOo19AX3j4, Mar 17, 2019.