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Batch 'A',lTMMC Brief Introduction
Nuclei & Origin
Greater Petrosal Nerve
Chorda Tympani Nerve
Applied Anatomy What Are We Discussing : 1.Brief Introduction
4.Nuclei & Origin
8. Applied Anatomy What Are We Discussing : 1.Why Is Facial Nerve So Important? 2. EMBRYOLOGY Sensory & Motor Roots
Branchial Arch System
Pretrematic Nerve SENSORY
Role of Neural Crest Cells
Neurobiotaxis SENSORY AND MOTOR ROOTS Nerve of 2nd Branchial Arch
Muscles of facial expression, Posterior Belly of Digastric, Stylohyoid and Stapedius.
Skeletal Component BRANCHIAL ARCH SYSTEM 1-General Somatic Afferent or GSA: Perception of touch, pain and temperature from the surface of the skin Temperature Pain Touch 2-General visceral afferent or GVA: Sensory input
from viscera 3-General Somatic Efferent or GSE:
Motor innervation to skeletal muscles 4-GVE: Motor innervation to smooth muscle, heart muscle and glands 5-Branchial efferent[BE]: Motor innervation to skeletal muscles derived
from pharyngeal arch mesoderm Note: BE is also called special visceral efferent[SVE]
Special senses: SSA- vision,
hearing and balance, SVA: taste and smell Functional components of facial nerve:
1-GSA: sensory supply to part of external acoustic meatus and deeper parts of auricle
2-SA: taste from anterior two thirds of tongue
3-GVE: parasympathetic supply to lacrimal, submandibular, sublingual glands, mucous membranes of nasal cavity, hard and soft palates
4-BE: Muscles derived from SECOND pharyngeal arch- muscles of facial expression, posterior belly of digastric, stylohyoid
Depends on the type of structure a nerve innervates and whether it carries afferent or efferent information
Spinal nerves have four functional components whereas cranial nerves have six
All of them may not be present in a single nerve 1-GSA- General Somatic Afferent
2-GVA- General Visceral Afferent
3-GSE- General Somatic Efferent
4-GVE-General Visceral Efferent
5-BE- Branchial Efferent
6-SA- Special Afferent NUCLEI & ORIGIN 5. INTRACRANIAL COURSE SCHEMATIC REPRESENTATION COURSE
Leaves the skull passing through the stylomastoid foramen
Runs forwards, enters the parotid & divides into 5 terminal branches 6. EXTRACRANIAL COURSE 1. Posterior auricular
It supplies: Auricularis posterior Occipitalis Intrinsic muscles on the back of auricle
3. Stylohyoid Branches At its exit from the stylomastoid foramen Branches emerging from the Parotid Gland Corrugator supercilii also known as the frontal branch
Supplies the auriculares anterior and superior
The more anterior branches supply the frontalis, the orbicularis oculi, and corrugator supercilii
acts as the efferent limb of the corneal reflex Temporal Orbicularis oculi supply the Orbicularis oculi
muscles of th nose
muscles between the eye & mouth Zygomatic Action
Aids chewing by holding cheeks flat
Elevates upper lip
Purse Lips Muscle
Levator Labii Superioris
Levator labii superioris alaeque nasi
Levator Anguli Oris
Orbicularis oris The lower deep branches supply the Buccinator and Orbicularis oris
The buccal branch innervates the muscles of facial expression Buccal Buccinator Nasalis Levator labii superioris
alaeque nasi Orbicularis oris Risorius Levator labii superioris The marginal mandibular branch innervates the following muscles:
Depressor labii inferioris - lowers bottom lip down and laterally..
Depressor anguli oris (triangularis) - lowers the corner of the mouth down and laterally
Mentalis - raises and protrudes lower lip as it wrinkles skin on chin Marginal mandibular Platysma
One branch descends to join the cervical cutaneous nerve from the cervical plexus; others supply the Platysma. Also supplies the depressor anguli oris. Cervical Branches off from the facial nerve at the geniculate ganglion
Exits the temporal bone through a small canal that opens via a fissure onto the anterior surface of the petrous part of the temporal bone.
Passes anteromedially along the posterior margin of the middle cranial fossa and then under the internal carotid artery to reach the superior surface of the cartilage filling the foramen lacerum.
Here it is joined by the deep petrosal nerve to form the nerve of the pterygoid canal.
The greater petrosal nerve carries parasympathetic innervation to all glands above the oral fissure, including
mucous glands in the nasal cavitysalivary glands in the upper half of the oral cavity; and
the lacrimal gland in the orbit.
The greater petrosal nerve also carries some taste (SA) fibers from the soft palate in the lesser palatine nerve It is a mixed visceral nerve containing taste fibres from the tongue(cell bodies in geniculate ganglion)& secretomotor fibres for salivary glands of the floor of the mouth[cell bodies in superior salivatory nucleus] in pons 8. CHORDA TYMPANI TRACING OF PARASYMPATHETIC SECRETOMOTOR FIBRES FOR SALIVARY GLANDS- Runs upwards & forwards in a bony canal
Enters middle ear & runs in close relation to tympanic membrane.
Leaves middle ear by passing to petrotympanic fissure.
It then passes medial to spine of sphenoid & enters infratemporal fossa.
Here it joins lingual nerve through which it is distributed
Pre ganglionic secretomotor fibres to sub mandibular ganglion for supply to submandibular & sublingual salivary glands
Taste fibres from ant 2/3rd of tongue except vallate papillae. COURSE Parasympathetic secretomotor supply originates in superior salivatory nucleus of facial nerve
Pre –ganglionic fibres pass to sub-mandibular ganglion & other small ganglia close to the duct through chorda tympani & lingual nerve.
Post ganglionic fibres reach sub mandibular gland either directly or along the duct
Post ganglionic fibres to sub lingual gland travel through lingual nerve DISTRIBUTION Nerve of Facial Expressions; also known as “QUEEN OF FACE”.
Important for Reflexes, i.e., STAPEDIAL REFLEX, CORNEAL REFLEX.
Paralysis more common ( As compared to other Cranial Nerves ). Sensory & Motor Roots
Branchial Arch System 3. FUNCTIONAL COMPONENTS 1.Motor Nucleus of facial ( Seventh ) nerve
2.Nucleus Tractus Solitarius
3.Spinal Nucleus of Trigeminal Nerve
4.Superior Salivatory Nucleus Mentalis Depressor Labii Inferioris Depressor Anguli Oris 1. Congenital Defects
6. Clinical Testing 8. CLINICAL ANATOMY 1. Congenital Defects
Moebius Syndrome Melkersson Rosenthal Syndrome
i)Bell’s Palsy 2. Infections
ii) Ramsay-Hunt Syndrome Birth Trauma
2.Compression moulding 3. Trauma ii) Temporal Bone Fractures
b- Transverse i) Central
ii) At / Around –
a- Geniculate Ganglion
b- Stylomastoid Foramen 4. Lesions Motor Functions -
Testing of Muscles – i) Frontalis
ii) Orbicularis oculi
v) Orbicularis oris
Sensory Functions - Tongue = Anterior 2/3rds
= TEST the TASTE 6. Clinical Testing 3. FUNCTIONAL COMPONENTS Depends on the type of structure a nerve innervates and whether it carries afferent or efferent information
Spinal nerves have four functional components whereas cranial nerves have six
All of them may not be present in a single nerve ii) Glomus 5. Tumours i) Acoustic Neuroma
The preganglionic parasympathetic fibres arise from the superior salivatory nucleus
the axons run in nervous intermedius
leave the facial nerve to enter the chorda tympani nerve
the submandibular ganglion (relay takes place)
to submandibular;sublingual gland and anterior lingual glands.
ROLE OF THE FIBRES-
They stimulate the secretion and are vasodilators. FACIAL Nerve has two components:-
SENSORY root In Internal Acoustic Meatus 2 roots- Motor & Sensory
Accompanied byAuditary Nerve & Labyrithine vessels
Enters Facial Canal In Facial Canal Twists & Turns…..
2 bends in the course divide the nerve in 3 parts
First bend is sharp- External Genu
Geniculate Ganglion (cell bodies of sensory fibres)
Branch- Greater Petrosal Nerve In Middle Ear Medial wall of Middle Ear
Goes backward, over promontory
On reaching posterior wall takes 2nd bend
Goes vertically downward
Branches- a) to stapedius, b)chorda tympani 3 IN NUMBER :
3. Geniculate 7. GANGLIA 1. Pterygopalatine Ganglion
Present in the pterygopalatine fossa
Associated with the maxillary nerve structurally and to the greater petrosal nerve functionally
Preganglionic fibres from the lacrimatory nucleus relay here through the greater petrosal nerve
Postganglionic fibres are distributed to the lacrimal gland via the zygomatic nerve and to glands in the nasal cavity and palate through palatine, nasal, infra-orbital and superior alveolar branches of the maxillary nerve 2. Submandibular Ganglion
Present superior to the submandibular gland
Preganglionic fibres from the superior salivatory nucleus reach the ganglion via the chorda tympani nerve, which joins with the lingual nerve to reach the ganglion
They synapse in the ganglion, and the postganglionic fibres innervate the submandibular and sublingual glands, and other glands in the oral cavity below the level of the oral fissure either directly or be again joining the lingual nerve
The facial nerve enters the internal acoustic meatus and then passes between the internal and middle ears
Before it bends posteriorly and laterally to run down the posterior wall of the middle ear, it enlarges to form the geniculate ganglion
It contains cell bodies of
1- nerve fibres that carry taste from anterior two-thirds of tongue, which are then relayed to the NTS
2-GSA fibres that innervate skin of the external ear and external acoustic meatus, the information is then relayed to the spinal nucleus of the trigeminal nerve OVERVIEW OF BRANCHES AND GANGLIA REFERANCE: Gray's Anatomy
Neuroanatomy by Vishram singh
Embryology by Keith Moore
Netter's Atlas of Human Anatomy
B D Chaurasia THANK YOU 7.GREATER PERTOSAL