Ophthalmic Branch of the Trigeminal Nerve
Its first division is the ophthalmic branch, which consists of afferent sensory fibers. The word afferent means toward the centre, as in from a peripheral area of a limb to the central nervous system. The word efferent is the opposite of afferent, meaning away from the centre and toward the periphery; when the stimulus is carried back to the brain from a peripheral area.
The ophthalmic nerve is a purely sensory nerve. Its branches carries sensory information from the eye, orbit, forehead, anterior scalp, frontal and ethmoid sinuses.
Pathway & Branches
The pathway for afferent sensory fibers of the ophthalmic nerve from the proprioceptors until the trigeminal nuclei (after the merger into one main cranial nerve) is the following (from the initiation in the periphery to the termination in the brain):
- The ophthalmic area consists of the following nerves: the anterior ethmoidal nerve which gives external and internal nasal branches; the supratrochlear and infratrochlear nerves; the supraorbital nerve; the long and short ciliary nerves, which contain postganglionic fibers from the ciliary ganglion; the frontal nerve and the lacrimal nerve.
- Both the preganglionic fibers from the ciliary ganglion and fibers from the peripheral branches merge into the ophthalmic branch.
- The ophthalmic branch gives off a recurrent tentorial branch which supplies the tentorium cerebelli and supratentorial falx cerebri.
- The ophthalmic nerve then synapses on the trigeminal ganglion, otherwise known as the semilunar Gasserian ganglion.
- The fibers then continue to the pontine nucleus and then the spinal nucleus and spinal tract.
- The ophthalmic nerve is the first of three main branches of the trigeminal nerve (CN V).
- The ophthalmic nerve branches enter the orbit through the superior orbital fissure, then courses on the lateral wall of the cavernous sinus before synapsing at the trigeminal ganglion.
- The ophthalmic nerve is purely sensory. Also, its lacrimal branch receives postganglionic parasympathetic fibers from the zygomatic branch of the maxillary nerve.
- The ophthalmic nerve main branches are:
- Nasociliary branch.
- Lacrimal branch.
- Frontal branch
- Tentorial branch.