ANES

ANESTHESIOLOGY - Ophthalmic Division of the Trigeminal Nerve (V1)

Overview of the Ophthalmic Division

• Smallest of the three branches from the Semilunar Ganglion.

• Functions purely as a sensory nerve.

• Exits the skull through the Superior Orbital Fissure.

Sensory Functions

• The sensory or afferent fibers of the ophthalmic branch supply the following areas:

  • Scalp

  • Forehead

  • Upper eyelid

  • Lining of the frontal sinus

  • Conjunctiva of the eyeball

  • Lacrimal gland

  • Skin of the lateral angle of the eye

Communicating Branches

• Located in the middle cranial fossa, the nervus tentorii branches supply the dura mater.

• Gives off communicating branches to:

  • Oculomotor Nerve (CN III)

  • Trochlear Nerve (CN IV)

  • Abducent Nerve (CN VI)

Cavernous Sinus

• The ophthalmic division (V1) and maxillary division (V2) pass through the cavernous sinus.

• As V1 passes forward through the cavernous sinus, it divides into three main branches:

  1. Lacrimal Nerve

  2. Frontal Nerve

  3. Nasociliary Nerve

• Cavernous Sinus is significant because if an infection reaches it, it can affect the ophthalmic nerve and other nerves. This area also contains major structures such as the internal carotid artery, maxillary and mandibular nerves.

Branches of the Ophthalmic Division

I. Lacrimal Nerve

• The smallest of the three branches.

• Passes into the orbit at the lateral angle of the superior orbital fissure, reaching the lacrimal gland.

• Supplies:

  • Lacrimal gland

  • Conjunctiva of the eye

II. Frontal Nerve

• The largest of the three branches of V1.

• Appears to be a "direct continuation" of V1.

• Branches of the Frontal Nerve:

  • A. Supraorbital Nerve

  • Larger branch leaving the orbit through the supraorbital foramen.

  • Innervates:

    • Skin of the upper eyelid

    • Forehead

    • Anterior scalp region to the vertex

  • B. Supratrochlear Nerve

  • Supplies skin of the upper eyelid and the lower medial portion of the forehead.

  • Note: The supraorbital and supratrochlear nerves overlap in innervation.

III. Nasociliary Nerve

• Branches in the Orbit:

  1. Long Root of the Ciliary Ganglion

  • Supplies the eyeball via short ciliary nerves.

  1. Long Ciliary Nerve

  • Supplies the eyeball, specifically the iris and cornea, as a direct branch of the nasociliary nerve.

  • Ciliary Nerves:

    • Long and short ciliary nerves supply the eyeball.

    • Long root of the ciliary ganglion is the whole nerve directly branching from the nasociliary.

    • Short ciliary nerves branch off from the ciliary ganglion.

  1. Posterior Ethmoid Nerve

  • Supplies posterior ethmoidal cells and the sphenoid sinus.

  1. Anterior Ethmoid Nerve

  • Supplies mucous membranes of the anterior ethmoidal cells and frontal sinus.

  • Internal Nasal Branches:

    • i. Medial or Septal Branch - Supplies mucous membrane of the medial nasal septum.

    • ii. Lateral Branch - Supplies superior and middle conchae and anterior lateral nasal wall.

  • External Nasal Branch - Supplies skin over the tip of the nose and ala of the nose.

Additional Information on Nasociliary Nerve

• Branches arising in the nasal cavity:

  • Supplies mucous membranes of the nasal cavity.

• Terminal branches:

  • Supplies skin of the medial part of the eyelids.

  • Supplies lacrimal sac and lacrimal caruncle.

  • Supplies the side of the bridge of the nose.

Basic Terms Defined

• Orbit: Houses the eyeballs.

• Lateral: Refers to external sides.

• Conjunctiva of the Eye: The red part of the eye below.

• Supra: Means above.

• Vertex: The highest point of the skull, based on height.