Dr. M. Elmubarak:

MBBS , Msc clinical anatomy, MD registrar of orthopedic and trauma surgery

Objective

Review the functinal component of cranial nerve

Type , neucli and applied anatomy of trigeminla

nerve

Type , neucli and applied anatomy of facial nerve

Type , neucli and applied anatomy of

vestibulocochlear nerve

CRANIAL NERVES

Types :

Pure sensory: The olfactory, optic and

vestibulocochlear nerves

Pure motor: the oculumotor, trochlear, abducent,

accessory and hypoglossal nerves

Mixed nerves: the remaining nerves.5,7,9,10

Functional componant of cranial nerves:

G: general, S:somatic , V:vesciral,E: efferent, A: afferent B:branchial.

GSA (exteroception)

GVA (visceral sensation)

SVA (special sense)

SSA (special senses)

GSE (sk muscle)

GVE (sm muscle, gland)

SVE (BE, pharyngeal arch)

(Trigeminal (SVE, GSA

Type:

The trigeminal is mixed cranial nerve has:

Sensory supply to face, the greater part of the scalp, the

teeth, the oral & nasal cavities (axons of cells in the

trigeminal ganglion , sensory neuclus)

The motor supply to the masticatory & some other

muscles.(motor nucleus)

the largest cranial nerve

It has three divisions

1. OPHTHALMIC

2. MAXILLARY

3. MANDIBULAR.

NUCLEI:

Sensory nucleus :

Principle : in the pons , receive touch

Spinal : in medula and upper spinal cord, receive pain and

tempreture.

Mesoecephalic: in the midbrain, receive proprioception

Motor nucleus

In the pons

Send fiber to mandibular division

APPLIED ANATOMY:

LESION OF TRIGEMINAL NERVE: A lesion of the whole trigeminal nerve causes

Anaesthesia of the anterior half of the scalp, of the face (except a small area near the angle of mandible), of the cornea & conjunctiva, the mucosae of the nose,mouth and presulcal part of the tongue.

Paralysis and atrophy occur in the muscles supplied by the nerve also.

TRIGEMINAL NEURALGIA characterized by pain in the distribution of branches of the trigeminal nerve, is the most common condition affecting the sensory part of the nerve.

Facial Nerve (SVE, SVA, GVE)

Type:

Consists of a motor & sensory (nervus intermedius) roots.

The motor root mainly supplies muscles of face, stapedius &

stylohyoid.

The sensory root conveys from the chorda tympani gustatory

fibers from the anterior 2/3 of tongue

it also carries preganglionic parasympathitic innervation of

the submandibular & sublingual salivary glands, lacrimal

glands. Nose and palat

NUCLEI:

Motor nucleus of facial : for muscle supplied by the

nerve. in the pons.

Superior Salivatory Nucleus: for pterygopalatine

Ganglion and submandibular ganglion. In the pons

Nucleus of Tractus Solitarius :for Taste fibers, anterior

2/3 of tongue. In the medulla

APPLIED ANATOMY:

Lesion: The paralysis may be UMN or LMN:

Upper motor neuron facial paralysis,

Lower face but not the upper (forehead and orbicularisoculi) because the facial nerve nucleus innervating the upper part of face receives fibers from cerebral cortex of both sides whereas the lower part innervating the lower part of the face receives contralateral fibers.

However emotional movements of the lower face, as in smiling and laughing, are still possible (presumably there is an alternative pathway from the cerebrum).

Lower motor neuron fascial palsy lesions: upper and lower fascial muscle paralysis

Lesions of facial nerve in the facial canal may

involve nerve to stapedius causing excessive

sensitivity to sound in one ear. Hyperacousis

When damage is in the petrous temporal bone,

chorda tympani is usually involved resulting in loss

of taste from anterior two thirds of the tongue.

VESTIBULOCOCHLEAR NERVE(8TH):

Type:

The vestibulocochlear nerve (CN-VIII), is main sensory

supply of internal ear.

It has two major sets of fibers,

Vestibular nerve, concerned with equilibration and arising

from the vestibular ganglion in the outer part of internal

acoustic meatus.

Cochlear nerve, concerned with audition arising from the

neurons in the spiral ganglion of the cochlea.

NUCLEI:

Special Somatic Afferent: Two cochlear nuclei in Pons

for HEARING.

Special Somatic Afferent: Four vestibular nuclei in Pons

& Medulla for EQUILIBRIUM.

INTRACRANIAL COURSE:

The nerve emerges in the groove between the pons and

the medulla oblongata, behind the facial nerve.

Ventral view

APPLIED ANATOMY :

Disturbances of vestibular nerve function include

giddiness (VERTIGO) and NYSTAGMUS.

Disturbances of the cochlear nerve function produce

DEAFNESS and TINNITUS.