DR. M. MD. MUSTAFA SHARIFF DEPARTMENT OF ANATOMY SENIOR LECTURER SRMDC -2021 INTRODUCTION
• It is fifth and largest cranial nerve. • It is mixed nerve ( sensory and motor) SENSORY TO ✓ Skin of face ✓ Mucosa of cranial viscera ✓ Except base of tongue and pharynx
MOTOR TO ✓ Muscle of mastication ✓ Tensor ville palatine ✓ Tensor tympani ✓ Anterior belly of digastric ✓ Mylohyoid
TRIGEMINAL NUCLEI
• A cranial nerve nucleus is a collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerve.
• Axon carrying information to and from the cranial nerves form a synapse first at these nuclei.
• Lesion occurring at the nuclei can lead to effects resembling those seen by the severing of nerves they are associated with.
SENSORY NUCLEI
MESENCEPHALIC NUCLEUS
• Cell body of Pseudounipolar neuron
• Relay proprioception from muscle of mastication,
• Extra ocular muscle,
• Facial muscle
• Situated in midbrain just lateral to aqueduct PRINCIPAL SENSORY NUCLEUS.
• Lies in pons lateral to motor nucleus
• Relays touch sensation
SPINAL NUCLEUS
• Extends from caudal end of principal sensory nucleus in pons to 2nd or 3rd spinal segment
• It relays pain and temperature MOTOR NUCLEUS
• Innervates muscles of mastication and tensor tympani and tensor palatini
• Derived from first branchial arch
• Located in pons medial to principal sensory nucleus
FUNCTIONAL COMPONENT
SPECIAL VISCERAL EFFERENT (SVE): • Fibers arise from motor nucleus and supply the muscle s derived from the first pharyngeal arch mesoderm.
✓ Muscle of mastication ✓ Tensor ville palatine ✓ Tensor tympani ✓ Anterior belly of digastric ✓ Mylohyoid GENERAL SOMATIC AFFERENT (GSA): • GSA fibers are divided into two groups.
• Fibers carrying exteroceptive sensation from skin of the face and mucous membrane of the mouth and nose.
• The cell bodies of these neurons lie in the trigeminal ganglion.
• Most of the central processes of these neurons bifurcate, the ascending branches terminate in the chief sensory nucleus whereas descending branches end in the spinal nucleus. • Fibers carrying proprioceptive sensation from muscles of mastication, temporomandibular joint, teeth and tongue.
• The cell bodies of these neurons lie In the Mesencephalic nucleus.
• The peripheral processes of nerve cells located in the trigeminal ganglion and Mesencephalic nucleus are arranged into three division of trigeminal nerve.
• OPHTHALMIC -GSA FIBERS • MAXILLARY -GSA FIBERS • MANDIBULAR -GSA AND SVE FIBERS
COURSE AND DISTRIBUTION
• Both motor and sensory root are attached ventrally to junction of pons and middle cerebellar peduncle with motor root lying ventro medially to the sensory root.
• Pass anteriorly in middle cranial fossa to lie below tentorium cerebelli in cavum trigeminale , here motor root lies inferior to sensory root. • Sensory root connected to postro medial concave border of the trigeminal ganglion.
• Convex antrolateral margin of the ganglion gives attachment to the 3 division of the trigeminal nerve.
• Motor root turns further inferior with sensory component of V3 to emerge out of foramen ovale as mandibular nerve.
• Ophthalmic and maxillary division emerges through superior orbital fissure and foramen rotundum.
CLINICAL ANATOMY • Lesion of trigeminal nerve present following clinical feature.
• Loss of general sensation from face and mucous membrane of oral and nasal cavities.
• Loss of corneal reflex
• Paralysis of muscles of mastication.
• Jaw deviated to the side of lesion due to unopposed action of lateral pterygoid muscle. • HYPOACUSIS ( partial deafness to low pitched sounds due to paralysis of tensor tympani muscle).
TRIGEMINAL NEURALGIA (TIC DOULOUREUX) • Is paroxysmal sever pain of sudden onset and short duration in the area of cutaneous distribution of one or more of the division of the trigeminal nerve, usually affecting the 2nd and 3rd division. REFERENCES ➢ TEXT BOOK OF ANATOMY HEAD NECK AND BRAIN VOL III VISHRAM SINGH ➢ EXAM-ORINTED ANATOMY SHOUKAT N.KAZI ➢ HEAD & NECK AK DATTA 5TH EDITION ➢ GRAYS ANATOMY STUDENTS EDITION ➢ CLINCAL ANATOMY SNELL 8TH EDITION ➢ CLINICAL ANATOMY MOORE 5TH EDITION ➢ HEAD & NECK BD CHAURASIA’S 4TH EDITION ➢ HEAD & NECK DR.AS.MONI