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OPHTHALMIC (V1) NERVE

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OPHTHALMIC (V1) NERVE

OPHTHALMIC (V1): TRIGEMINAL NERVE
  • First division of the trigeminal nerve.
  • Pure sensory nerve.
  • Smallest of the three divisions of the trigeminal.
  • Function- General sensation (touch, pain & temperature).
  • Cranial exit point- superior orbital fissure.
  • 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:

1. Supratrochlear 

2. 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:

  • 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:

  • Long root of the ciliary ganglion
  • Long ciliary
  • Infratrochlear nerve
  • Ethmoidal nerves.

a. SENSORY ROOT TO 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:

  • 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.

d. Ethmoidal branch:

  • Supply the ethmoidal cells of ethmoidal sinus

Anterior ethmoidal nerve supplies –

– middle & anterior ethmoidal air sinus

– nasal cavity, and skin on the tip of the nose

– anterior cranial fossa

  • 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 Important

  • 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, 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. 
  • Function- General sensation (touch, pain & temperature).
  • Cranial exit point- superior orbital fissure.
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