TRIGEMINAL NERVE

INTRODUCTION:
  • Largest cranial nerve, Passes through Meckel's cave.
  • Trigeminal nerve is derived from 1st pharyngeal arch
  • Large sensory root: carries sensation from the skin and mucosa of most of the head.
  • Smaller motor root: innervates most of the chewing muscles (masseter, temporalis, pterygoids, mylohyoid), and the tensor tympani muscle of the middle ear.
  • The efferent fibers originate in the motor nucleus of V in the pons and controls the muscles involved in chewing.
  • The sensory root (the main portion of the nerve) arises from cells in the semilunar ganglion (also known as the Gasserian, or trigeminal, ganglion) in a pocket of dura (Meckel's cavity) lateral to the cavernous sinus.
NUCLEI OF TRIGEMINAL NERVE:
  • Main sensory nuclei(situated in upper pons)
  • Spinal nuclei (sensory in upper pons to C2 segment of spinal cord)
  • Mesencephalic nuclei(sensory in midbrain)(to massetric muscle)
  • Motor nuclei (situated in upper pons)
THE TRIGEMINAL GANGLION :
  • Also known as Gasserian ganglion, or semilunar ganglion, is a sensory ganglion of the trigeminal nerve that occupies a cavity (Meckel's cave) in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone.
  • It is somewhat crescentic or semilunarinshape, with its convexity directed anteriomedialy.
  • The three divisions of the trigeminal nerve emerges from this convexity.
ASSOCIATED ROOTS AND BRANCHES:
  • The central processes of the ganglion cells form the large sensory root of the trigeminal nerve ,which is attached to pons at its junction with the middle cerebellar peduncle. The peripheral processes form the three divisions of the trigeminal nerve.
  • The small motor root of the trigeminal nerve is attached to the pons superomedialy to the sensory root.
  • It passes under the ganglion from its medial to the lateral side and joins the mandibular nerve at the foramen ovale.
RELATIONS:
  • MEDIALLY- Internal carotid artery & posterior part of cavernous sinus
  • LATERALLY-Middle meningeal artery
  • SUPERIORLY- Parahippocampal Gyrus
  • INFERIORLY-Motor root of trigeminal nerve, greater petrosal nerve, apex of the petrous temporal bone & foramen lacerum
BRANCHES:

Branches Functional Components Cells of Origin / Termination Cranial Exit Distribution and Functions
Ophthalmic division (CN V') Superior orbital fissure Sensation from cornea, skin of forehead,
scalp, eyelids, nose, and mucosa of nasal cavity and paranasal sinuses
Maxillary division (CN V2) General sensory Trigeminal ganglion/spinal, principal and mesencephalic nucleus of CN V Foramen rotundum Sensation from skin of face over maxilla including upper lip,
maxillary teeth, mucosa of nose, maxillary sinuses, and palate
Mandibular division (CN V3) Foramen ovale Sensation from the skin over mandible,
including lower lip and side of head
mandibular teeth, temporomandibular
joint, and mucosa of mouth and anterior
two thirds of tongue
Branchial motor Foramen ovale Motor to muscles of mastication,
mylohyoid, anterior belly of digastric,
tensor veli palatini, and tensor tympani
Exam Question
  • Spinal nuclei is nuclei of trigeminal nerve
  • Mesencephalic nuclei of trigeminal nerve give sensory supply to massetric muscle
  • The third branch of trigeminal nuclei emerges from foramen ovale
  • Sensation from skin of face is carried by trigeminal nerve fibers from mesencephalic nucleus
  • The third branch of trigeminal nerve gives motor supply
  • Corneal reflex is due to trigeminal nerve innervation
  • Anterior belly of digastric muscle is supplied by 3rd division of trigeminal nerve
  • Tensor tympani muscle is supplied by 3rd division of trigeminal nerve
Don't Forget to Solve all the previous Year Question asked on TRIGEMINAL NERVE