Opthalmic Division Of Trigeminal Nerve

INTRODUCTION:
  • First division of the trigeminal nerve.
  • It Is a sensory nerve.
  • Smallest of the three divisions of the trigeminal.
  • Arises from upper part of the semi lunar ganglion as a short, flattened band, passes forward along the lateral wall of the cavernous sinus.
  • Varicella zoster virus lying dormant within the trigeminal ganglion can reactivate and spread through the ophthalmic division of the trigeminal nerve. 
BRANCHES:
  • Before entering the orbit through superior orbital fissure, it divides into three branches,
  • Lacrimal
  • Frontal and
  • Nasociliary.
1. LACRIMAL NERVE:
  • Smallest of the three branches.
  • Enters orbit through the narrowest part of the superior orbital fissure.
  • In orbit runs along the upper border of the lateral Rectus with the lacrimal artery communicates with the zygomatic branch of the maxillary nerve.
  • Enters the lacrimal gland gives off several fibers, which supply the gland and the conjunctiva.
  • Finally pierces the orbital septum ends in the skin of the upper eyelid, joining with nerve fibers of the facial nerve. 
2. FRONTAL NERVE:
  • Largest branch of ophthalmic.
  • Enters the orbit - superior orbital fissure and runs forward between the Levator palpebral superioris and the periosteum.
  • Most frequently involved in herpes zoster ophthalmicus 
  • Midway between the apex and base of the orbit it divides into two branches
  • Supratrochlear
  • Supraorbital
a. SUPRATROCHLEAR NERVE:
  • Smaller of the two .
  • Escapes from the orbit between the superior oblique and the supraorbital foramen.
  • Supplies skin of the lower part of the forehead close to the middle line 
  • Sends fibers to the conjunctiva and skin of the upper eyelid. 
b. SUPRAORBITAL NERVE:
  • Passes through supraorbital foramen & gives off palpebral filaments to the upper eyelid.
  • Then ascends upon the forehead and ends in two branches Medial & Lateral which supply the integument of the scalp, reaching nearly as far back as the lambdoidal suture.
  • Both branches supply small twigs to the pericranium.
3.NASOCILIARY NERVE:
  • Intermediate in size b/w the frontal and lacrimal and is more deeply placed.
  • Enters orbit b/w the two heads of the lateral Rectus and between the superior and inferior rami of the occulomotor nerve to medial wall of the orbital cavity.
  • Passes through the anterior ethmoidal foramen and enters the cranium.
  • Supplies Internal nasal branches to the mucous membrane of the front part of the septum and lateral wall of the nasal cavity.
  • Anterior ethmoidal artery accompanies the Nasociliary nerve 
  • Finally emerges as external nasal branch b/w the lower border of nasal bone and the lateral nasal cartilage passing down beneath the Nasalis muscle - supplies the skin of the ala and apex of the nose.
  • If a patient has herpes zoster and tip of the nose is affected it means the nasociliary nerve is affected and eye will definitely get involved. This is known as the Hutchison’s rule.
  • Branches of nasociliary:
  1. Long root of the ciliary ganglion
  2. Long ciliary
  3. Infratrochlear nerve
  4. Ethmoidal nerves.
a. LONG ROOT OF CILIARY GANGLION:
  • Supplies ciliary ganglion.
b. Long Ciliary Nerve:Two or three in number Accompany the short ciliary nerves from the ciliary ganglion - pierce the posterior part of the sclera and running forward b/w it and the choroid distributed to the iris and cornea.
c.Infratrochlear nerve:
  • Given off from nasociliary just before it enters the anterior ethmoidal foramen.
  • Runs forward along the upper border of the medial Rectus.
  • Then passes to medial angle of the eye.
  • Supplies skin of the eyelids and side of the nose, the conjunctiva, lacrimal sac, and caruncula lacrimalis.
c.Ethmoidal branch:
  • Supply the ethmoidal cells of ethmoidal sinus
  • Anterior ethmoidal nerve supplies the ethmoid sinus, nasal cavity, and skin on the tip of the nose.
  • Dura mater of anterior cranial fossa is supplied by anterior and posterior ethmoidal nerves. 
  • Posterior branch leaves the orbital cavity through the posterior ethmoidal foramen and gives some filaments to the sphenoidal sinus.
FUNCTIONS:
  • Transmits sensory innervations from Eye ball, Skin of upper face, Anterior scalp, Lining of upper part of nasal cavity, air cells & Meninges of anterior cranial fossa.
  • Conveys parasympathetic fibers to the ciliary and iris muscle for accommodation and pupillary constriction and to the lacrimal gland. 
Exam Question
  • Varicella zoster virus lying dormant within the trigeminal ganglion can reactivate and spread through the ophthalmic division of the trigeminal nerve. 
  • Largest branch of ophthalmic nerve is frontal nerve
  • Most frequently involved in herpes zoster ophthalmicus branch of ophthalmic nerve is frontal nerve
  • Anterior ethmoidal artery accompanies the Nasociliary nerve
  • If a patient has herpes zoster and tip of the nose is affected it means the nasociliary nerve is affected and eye will definitely get involved. This is known as the Hutchison’s rule.
  • Supply the ethmoidal cells of ethmoidal sinus
  • Anterior ethmoidal nerve supplies the ethmoid sinus, nasal cavity, and skin on the tip of the nose. 
  • Dura mater of anterior cranial fossa is supplied by anterior and posterior ethmoidal nerves.

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