The
oculomotor nerve is the third
cranial nerve. It enters the
orbit via the
superior orbital fissure and innervates muscles that enable most movements of the eye and that raise the eyelid. The nerve also contains fibers that innervate the muscles that enable pupillary constriction and accommodation (ability to focus on near objects as in reading). The oculomotor nerve is derived from the
basal plate of the
embryonic midbrain. Cranial nerves
IV and
VI also participate in control of
eye movement.