Structure and Pathway
- Nasociliary nerve bifurcates into infratrochlear and anterior ethmoidal nerves.
- Infratrochlear nerve travels anteriorly in the orbit along the upper border of the medial rectus muscle.
- Infratrochlear nerve exits the orbit medially.
- Infratrochlear nerve passes underneath the trochlea of the superior oblique muscle.

Distribution of Sensory Innervation
- Infratrochlear nerve provides sensory innervation to the skin of the eyelids.
- Infratrochlear nerve provides sensory innervation to the conjunctiva.
- Infratrochlear nerve provides sensory innervation to the lacrimal sac.
- Infratrochlear nerve provides sensory innervation to the lacrimal caruncle.
- Infratrochlear nerve provides sensory innervation to the side of the nose superior to the medial canthus.

Communications
- Infratrochlear nerve receives a descending communicating branch from the supratrochlear nerve.

Etymology
- Infratrochlear nerve is named after the structure it passes under.
- 'Infratrochlear' means below the trochlea.
- 'Trochlea' refers to a fibrocartilaginous loop at the superomedial surface of the orbit.
- Trochlea is the passage for the tendon of the superior oblique muscle.

Additional Information
- Nerves of the orbit can be seen from above.
- Infratrochlear nerve is labeled as a terminal branch of the nasociliary nerve.
- Infratrochlear nerve is shown along with the anterior ethmoidal nerve.