Four muscles attach to the surface of the eye and work together to move the eyeball in a vertical (upward) direction. Two of those muscles, the superior and inferior rectus, move the eye up and down when the eye is rotated away from the nose. When the eye is turned toward the nose, the inferior oblique muscle is responsible for elevating the eye, turning the top of it away from the nose, and moving it outward.

When the eye is looking directly forward, all four muscles help create vertical movement, with the rectus muscles doing half the work and the two oblique muscles performing the other half.

The inferior oblique originates from a point in the middle and toward the front of the floor of the eye socket, near the tear duct. It passes below the inferior rectus muscle before inserting into the back of the sclera, the outer covering of the eye. This muscle, along with three of the rectus muscles, is supplied by the oculomotor (third cranial) nerve, which is also responsible for opening the eye.