The eye muscles are the most active in the body, moving more than 100,000 times a day.
There are six extraocular muscles that move the globe (eyeball). These muscles are named the superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique.
Upgaze, or turning the eye upward, is primarily the work of the superior rectus muscle, with some contribution by the inferior oblique muscle.
Downgaze, or turning the eye downward, is primarily the work of the inferior rectus, with some contribution by the superior oblique.
Abduction, or turning the eye outward toward the ear, is primarily done by the lateral rectus.
Adduction, or turning the eye inward toward the nose, is primarily done by the medial rectus.
The eye is rotated medially by the superior rectus and superior oblique and is rotated laterally by the inferior rectus and inferior oblique. In addition, the levator palpebrae superioris muscle, which is not seen on the drawing, elevates the eyelid.
The extraocular muscles are innervated by three cranial nerves (CN), CN III (oculomotor nerve), CN IV (trochlear nerve), and CN VI (abducens nerve). The relationship between the cranial nerve nuclei in the brainstem, the cranial nerves, and the muscles that the nerves innervate can be visualized in the schematic below.