Infratrochlear nerve

Not to be confused with supratrochlear nerve.

The infratrochlear nerve is a branch of the nasociliary nerve (itself a branch of the ophthalmic nerve (CN V₁)) in the orbit. It exits the orbit inferior to the trochlea of superior oblique. It provides sensory innervation to structures of the orbit and skin of adjacent structures.^{[1]: 631, 783}

Infratrochlear nerve
Sensory innervation of the head. The infratrochlear nerve is seen in the green area, emerging from the orbit.
Details
From	Nasociliary nerve
Innervates	Skin of eyelids, conjunctiva, lacrimal sac, lacrimal caruncle, side of nose above medial canthus
Identifiers
Latin	nervus infratrochlearis
TA98	A14.2.01.035
TA2	6214
FMA	52693
Anatomical terms of neuroanatomy [edit on Wikidata]

Structure

The nasociliary nerve terminates by bifurcating into the infratrochlear and the anterior ethmoidal nerves. The infratrochlear nerve travels anteriorly in the orbit along the upper border of the medial rectus muscle and underneath the trochlea of the superior oblique muscle. It exits the orbit medially and divides into small sensory branches.^{[2][verification needed]}

Distribution

The infratrochlear nerve provides sensory innervation to the skin of the eyelids, the conjunctiva, lacrimal sac, lacrimal caruncle, and the side of the nose superior to the medial canthus.^{[1]: 631, 783}

Communications

The infratrochlear nerve receives a descending communicating branch from the supratrochlear nerve.^[1]: 782

Etymology

The infratrochlear nerve is named after a structure it passes under. Infratrochlear means "below the trochlea". The term trochlea means "pulley" in Latin. Specifically, the trochlea refers to a fibrocartilaginous loop at the superomedial surface of the orbit called the trochlea, through which the tendon of the superior oblique muscle passes.

Additional images

• 
  Nerves of the orbit. Seen from above. The infratrochlear nerve is labelled at the top left, and can be seen as a terminal branch of the nasociliary nerve, along with the anterior ethmoidal nerve.