DR. DIBAKOR BHATDR. DIBAKOR BHAT

HMO, Department of NeurologyHMO, Department of NeurologyDhaka Medical College HospitalDhaka Medical College Hospital

05.04.2014

DEVELOPMENTTrigeminal nerve:Metencephalon,Mesencephalon

Facial nerve:Metencephalon,Myelencephalon

Vestibulocochlear nerve:Myelencephalon

DEVELOPMENT

TRIGEMINAL NERVE

TRIGEMINAL NERVE

Largest cranial nerve

Nuclei1.The main sensory nucleus

2.The spinal nucleus3.The mesencephalic nucleus

4.The motor nucleus

The main sensory nucleus: It lies in the posterior part of the

Pons, lateral to the motor nucleus. It is continuous below

with the spinal nucleus

The spinal nucleus: It is continuous superiorly with

the main sensory nucleus in the Pons and extends inferiorly through the whole length of the medulla oblongata and into the

upper part of the spinal cord as far as the second cervical

segments

The mesencephalic nucleus:

It is composed of a column of unipolar nerve cells in the lateral part of grey matter

around the cerebral aqueduct, extends

inferiorly into the pons as far as the main sensory

nucleus

The motor nucleus:It is situated in the pons

medial to the main sensory nucleus

Sensory branches of the trigeminal nerve

The ophthalmic, maxillary and mandibular branches leave the skull through three separate foramina:

superior orbital fissure, foramen rotundum and

foramen ovale

The ophthalmic nerve carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the

nose (including the tip of the nose), the nasal mucosa, the frontal sinuses and part of the meninges (the dura and blood vessels).

The maxillary nerve carries sensory information from the lower eyelid and cheek, the nares and upper lip, upper teeth and gums, nasal mucosa,

the palate and roof of pharynx, the maxillary, ethmoid and sphenoid sinuses and part of the meninges.

The mandibular nerve carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), part of the external ear and part of the

meninges.

Sensory branches of the trigeminal nerve

Touch & Pressure terminates into main sensory nucleus

Pain & Touch terminates into spinal nucleus

Ophthalmic division terminates into inferior part of spinal nucleus

Maxillary division terminates into medial part of spinal nucleus

Mandibular division terminates into inferior part of spinal nucleus

Motor branches of the trigeminal nerve Motor branches are distributed in the mandibular nerve, originate in

motor nucleus The motor branches of the trigeminal nerve control the movement of

eight muscles, including the four muscles of masticationMuscles of mastication massetertemporalismedial pterygoidlateral pterygoidOther tensor veli palatini mylohyoidanterior belly of digastrictensor tympani

All have bilateral cortical representation. A central lesion (e.g. stroke) is unlikely to produce any observable deficit. However, injury to the peripheral nerve can cause paralysis of muscles on one side of the jaw.

Course The trigeminal nerve leave the anterior aspect of the pons as a small motor root and a large sensory root. The nerve passes forward out of

the posterior cranial fossa and rests on the upper surface of the apex of the petrous part of the temporal bone in the middle cranial fossa.

The large sensory root now expand to form the crescent shaped trigeminal ganglion, which lies within a pouch of dura mater called the

trigeminal or meckel’s cave.

FunctionThe sensory function of the trigeminal nerve

is to provide the tactile, proprioceptive and nociceptive afferent of the face and mouth. The posterior scalp and the neck are innervated by C2-C3, not by the trigeminal nerve.

The motor function activates the muscles of the mastication, the tensor tympani, tensor veli palatini, mylohyoid, and anterior belly of the digastric.

FACIAL NERVE

FACIAL NERVEFacial nerve is a Mixed nerve

Nuclei

The main motor nucleus This lies deep in the reticular formation of the

lower part of the pons. The upper part of the nucleus that supplies the muscles of the upper part of the

face receives corticonuclear fibers from both cerebral hemisphere. The part of the nucleus supplies the lower part of the face receives

corticonuclear fibers only from the opposite cerebral hemisphere.

The parasympathetic nuclei:These lies posterlateral to the main motor

nucleus, they are: 1. Superior salivatory nucleus

2. Lacrimal nucleus

The sensory nucleus:This is the upper part of the nucleus of

the tractus solitarius and lies close to the motor nucleus.

Intracranial Course & Relation

Intracranial Course & Relation

Intracranial Course & Relation

Intracranial Course & Relation

Intracranial Course & Relation

Intracranial Course & Relation

Branches of VII nerve

Branches of VII nerve

Terminal Branches

Ganglia Associations

Geniculate ganglia

Submandibular ganglia

Pterygopalatine ganglia

Ganglia Associations

Ganglia Associations

Function

Efferent

1. Motor control of most of the muscles of facial expression, innervates the posterior belly of the digastric, stylohyoid and

stapedius muscle of the middle ear

2. The facial also supplies parasympathetic fibers to the submandibular gland and sublingual glands via chorda

tympani. Parasympathetic innervation serves to increase the flow of saliva from these glands. It also supplies

parasympathetic innervation to the nasal mucosa and the lacrimal gland via the pterygopalatine ganglion

3. Efferent limb of the corneal reflex

Function

Afferent

It receives taste sensations from the anterior two-thirds of the tongue and sends them to the nucleus of solitary tract

VESTIBULOCOCHLEAR NERVE

Vestibular nerve nuclei1. Lateral vestibular

nucleus2. Superior vestibular

nucleus3. Medial vestibular

nucleus4. Inferior vestibular

nucleus

Cochlear nerve nuclei1. Anterior cochlear

nuclei 2. Posterior cochlear

nuclei

Course

It emerges from the anterior surface of the brain between the lower border of the pons and

medulla oblongata and enters the inner skull via the internal acoustic meatus in the temporal

bone, along with the facial nerve.

FunctionThe vestibular nerve conducts nerve impulse

from Utricle and saccule: position of head

Semicircular canals: movement of head

The cochlear nerve conducts nerve impulse concerned with sound from the organ of corti