Infratrochlear nerve

The infratrochlear nerve is given off from the nasociliary just before it enters the anterior ethmoidal foramen.

It runs forward along the upper border of the medial rectus, and is joined, near the pulley of the superior oblique, by a filament from the supratrochlear nerve.

It then passes to the medial angle of the eye, and supplies the skin of the eyelids and side of the nose, the conjunctiva, lacrimal sac, and caruncle.

Etymology
Infratrochlear means "below the trochlea". The term trochlea means "pulley" in Latin. Specifically, the trochlea referred to is a loop inside the orbit of the eye (trochlea of superior oblique), through which the tendon of the superior oblique muscle passes.