Facial vii nerve

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FACIAL (VII) NERVE

FACIAL NERVE

  • The facial nerve is the seventh cranial nerve.
  • Mixed nerve consists of a motor and a sensory root.
  • Sensory part is frequently described under the name of nervous intermedius (nerve of Wrisberg or pas intermedii of Wrisberg).
  • It emerges from the brainstem between the pons and the medulla. 
  • It controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity.
  • It also supplies preganglionic parasympathetic fibers to several head and neck ganglia.
  • It is developmentally derived from the second pharyngeal arch.

PATHWAY OF FACIAL NERVE:

LOWER PONS 

__________________________________________l____(4 NUCLEUS)_____________________

l                                  l                                                                 l                                             l

MOTOR/BRACHIOMOTOR  SUPERIOR SALIVATORY (PARSYMPATHETIC)  LACRIMATORY(PARASYMPATHETIC)  NUCLEUS OF TRACTUS SOLITARUS

   l
l_______________________________________________l___________________________________l  

 MOTOR ROOT  SENSORY ROOT OR NERVUS INTERMEDIUS (2 roots attached medial to 8th C.N.  TO PONS)

l_ (laterally & forward )______________________________l

l

INTERNAL ACOUSTIC MEATUS

(here motor lies in groove with sensory root intervening; accompined by labyrinthine vessel)

l

TRUNK( MOTOR+ SENSORY ROOT at fundus of meatus)

l

PETROUS PART OF TEMPORAL BONE

l( in Facial canal)

 LABYRINTHINE SEGMENT(ends at genu 1st bend)

l

GENICULATE GANGLION (sensory nerve bodies) →  GREATER SUPERFICIAL PETROSAL NERVE

l

TYMPANIC SEGMENT(in tympanic cavity , medial to incus, ends at 2ndbend)

l→ NERVE TO STAPEDIUS

  l→  CHORDA TYMPANI→l

MASTOID SEGMENT  BONY l CANAL(in posterio medial wall of middle ear)

 l    MIDDLE l EAR

STYLOMASTOID FORAMEN   PTERGOTYMlPANIC FISSURE    

 l→ AURICULOTEMPORAL  INFRATEMlPORAL FOSSA

l→ DIGASTRIC   LINGUAL/  NERVE  \

l→ STYLOHYOID   SUBMANDIBULARlGANGLION      ANT. 2/3 OF TONGUE  

PAROTID GLAND SUBMANDIBULAR & SUBLINGUAL GLAND

l

PAROTID PLEXUS

___________________________l(splits into 5 branches)_____________

 l                    l                            l                         l                                     l

TEMPORAL      ZYGOMATIC    BUCCAL   MARGINAL MANDIBULAR  CERVICAL

 

BRANCHES OF FACIAL NERVE:

  • INTRACRANIAL:
  1. GREATER PETROSAL NERVE
  2. NERVE TO STAPEDIUS
  3. CHORDA TYMPANI 
  • EXTRACRANIAL: The arrangement of Branches of Facial nerve after exiting from Parotid gland is given the name asPes Anserinus
  1. AURICULOTEMPORAL
  2. DIGASTRIC
  3. STYLOHYOID
  • TERMINAL BRANCHES
  1. TEMPORAL
  2. ZYGOMATIC
  3. BUCCAL
  4. MARGINAL MANDIBULAR
  5. CERVICAL
BRANCHES  DISTRIBUTION FUNCTION
GREATER PETROSAL

  forms part of a chain of nerves that innervate the lacrimal gland & mucosal glands of the nose, palate, and pharynx.

  Parasympathetic
NERVE TO STAPEDIUS  stapedius muscle Helps muscle to damp excessive vibration on stapes 
CHORDA TYMPANI
  1. Submandibular & sublingual gland(preganglionicsecretomotor fiber)
  2. Ant. 2/3rd of tongue(taste fibers carried from here ) 
  1.  Salivation
  2. Taste sensation
AURICULOTEMPORAL
  1. Auricularis posterior
  2. Occipitalis
  3. Intrinsic muscle from back of pharynx
  controls movements of the scalp muscles which it supplies around the ear
DIGASTRIC  Posterior belly of digastric muscle  motor function
STYLOHYOID Stylohyoid muscle    motor function
TEMPORAL
  1. Auricularis anterior
  2. Auricularis superior
  3. Intrinsic muscle on lateral side of ear
  4. Frontalis
  5. Orbicularis oculi
  6. Corrugator supercilli 

 facial expression

corneal reflex
ZYGOMATIC  Orbicularis oculi  facial expression
BUCCAL
  1. Risorius
  2. Buccinator
  3. Levator Labii Superioris
  4. Levator labii superioris alaeque nasi
  5. Levator Anguli Oris
  6. Nasalis
  7. Orbicularis oris muscle
  8. Depressor Septi Nasi
  9. procerus
  1. Smile
  2. Aids chewing by holding cheeks flat
  3. Elevates upper lip
  4. snarl
  5. soft smile
  6. flare nostril
  7. purse lip
  8. depress nasal septum
  9. moves skin forehead
MARGINAL MANDIBULAR  Muscles of lower lip & chin  Motor function
CERVICAL
  1.  Platysma
  2. depressor anguli oris
  Motor function

 BLOOD SUPPLY OF  FACIAL NERVE:

  • The facial nerve gets it’s blood supply from 4 vessels:
  1. Anterior inferior cerebellar artery – at the cerebellopontine angle
  2. Labyrinthine artery  (branch of anterior inferior cerebellar artery) – within internal acoustic meatus
  3. Superficial petrosal artery (branch of middle meningeal artery) – geniculate ganglion and nearby parts
  4. Stylomastoid artery (branch of posterior auricular artery) – mastoid segment
  • The arteries form a external plexus lying within the epineurium and an internal plexus which in intraneural.
  • Venous drainage is from Venae comitantes of superficial petrosal and stylomastoid arteries.
Exam Question
 
  • Terminal branches of facial nerve are temporal, zygomatic, buccal, marginal mandibular & cervical
  • Branch of facial nerve passing through pterygotympanic fissure is chorda tympani
  • The arrangement of Branches of Facial nerve after exiting from Parotid gland is given the name as Pes Anserinus
  • Facial nerve is developmentally derived from the second pharyngeal arch
  • Chorda tympani is a branch of facial nerve
  • chorda tympani joins lingual nerve to supply submandibular gland and tongue
  • chorda tympani carries secretomotor fibers to submandibular & sublingual gland 
  • Chorda tympani branch of facial nerve carries taste sensation from anterior 2/3rd of tongue
  • Blood supply of facial nerve is by Anterior inferior cerebellar artery,Labyrinthine artery, Superficial petrosal artery, Stylomastoid artery 
  • The terminal branches of facial nerve are Temporal, Zygomatic, Buccal, Marginal mandibular & cervical
  • Facial nerve supplies lacrimal, mucosal ,sublingual , submandibular glands but not parotid
  • The muscles supplied by facial nerve include all muscles of face, scalp, auricle, eyelid, around mouth, neck
  • The intracranial branches of facial nerve are greater petrosal, stapedius, chorda tympani
  • All the muscles of the face are supplied by facial nerve except levator palpebrae superioris
  • Posterior belly of digastric is supplied by facial nerve
  • Greater petrosal nerve is the First branch of facial nerve.
  • stapedius is supplied by facial nerve
Don’t Forget to Solve all the previous Year Question asked on FACIAL (VII) NERVE

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