The tendon of the superior oblique passes through the trochlea and turns laterally to cross the eyeball in a posterolateral direction. It continues deep to the superior rectus muscle and inserts into the outer posterior quadrant of the eyeball.
Contraction of the superior oblique therefore directs the pupil down and out (Fig. 8.97A).
The trochlear nerve [IV] innervates the superior oblique along its superior surface.