Home > Encyclopedia of Neurological Disorders > Third Nerve Palsy

Definition

Third nerve palsy describes a condition involving the third cranial nerve (also called the oculomotor nerve), which is responsible for innervating some of the muscles responsible for eye movement.

Description

Third nerve palsy results in an inability to move the eye normally in all directions. Injury to the third nerve can occur anywhere along its path, from where it originates within the brain to where it innervates the muscles that move the eyeball. Third nerve palsy prevents the proper functioning of the medial, superior, and inferior recti, and inferior oblique muscles. As a result, the eye cannot move up, down, or in. When at rest, the eye tends to look down and to the side, due to an inequality of muscle functioning. The muscle responsible for keeping the upper eyelid open (levator palpebrae superioris) is also affected, resulting in a drooping upper eyelid (ptosis).

Causes and...