The infratrochlear nerve is a branch of the
nasociliary nerve
The nasociliary nerve is a branch of the ophthalmic nerve (CN V1) (which is in turn a branch of the trigeminal nerve (CN V)). It is intermediate in size between the other two branches of the ophthalmic nerve, the frontal nerve and lacrimal ner ...
(itself a branch of the
ophthalmic nerve (CN V1)) in the
orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
. It exits the orbit inferior to the
trochlea of superior oblique
{{wiktionary
Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel.
Related to joints
Most commonly, trochleae bear the articular surface of saddle and other joints:
* Trochlea of hu ...
. It provides sensory innervation to structures of the orbit and skin of adjacent structures.
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
The medial rectus muscle is a muscle in the orbit near the eye. It is one of the extraocular muscles. It originates from the common tendinous ring, and inserts into the anteromedial surface of the eye. It is supplied by the inferior division of t ...
and underneath the
trochlea of the
superior oblique muscle
The superior oblique muscle or obliquus oculi superior is a fusiform muscle originating in the upper, medial side of the orbit (anatomy), orbit (i.e. from beside the nose) which abducts, depresses and internally rotates the eye. It is the only e ...
. It exits the orbit medially and divides into small sensory branches.
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.
Communications
The infratrochlear nerve receives a descending communicating branch from the
supratrochlear nerve
The supratrochlear nerve is a branch of the frontal nerve, itself a branch of the ophthalmic nerve (CN V1) from the trigeminal nerve (CN V). It provides sensory innervation to the skin of the forehead and the upper eyelid.
Structure
Orig ...
.
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
File:Gray776.png, 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.
References
External links
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Ophthalmic nerve