Anatomy of Cranial Nerves 5,7,8
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Transcript of Anatomy of Cranial Nerves 5,7,8
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