Trochlea of superior oblique muscle

The trochlea of superior oblique muscle is a fibrocartilaginous pulley located in the anteromedial part of the orbit. It serves as a functional pulley for the tendon of the superior oblique muscle, changing the direction of the muscle’s pull before it inserts onto the eyeball.

Anatomical Description

• The trochlea is attached to the trochlear fossa of the frontal bone, just above the medial canthus.

• The tendon of the superior oblique passes forward from its origin (on the body of the sphenoid bone), loops through the trochlea, and then turns posterolaterally and downward to insert onto the posterior superior quadrant of the eyeball, behind the equator of the eyeball..

Functional Note

The trochlea acts as a fixed pulley, redirecting the line of pull of the superior oblique muscle.

• Before passing through the trochlea, the muscle pulls forward and medially.

• After looping through it, the tendon pulls the eyeball downward, outward, and medially, producing depression, abduction, and intorsion.

Thus, the trochlea is essential for the mechanical function of the superior oblique, converting its anterior pull into an effective posterior and downward force on the eyeball.