CN III – Occulomotor Nerve
021-cnIIIl

CN III (Occulomotor Nerve)

• Function
Eye movement and position through innervation of the dorsal, medial, and ventral recti, and the ventral oblique muscles
Also innervates the levator palpebrae muscle of the upper eyelid
PS to the pupil
• Assessment
The PS component is evaluated with the PLR.

- Movement
May assess voluntary eye movement or elicit vestibular eye movements by moving the head laterally. A normal patient will exhibit normal nystagmus, with the fast phase in the direction of the movement.

- Position
Normal positioning of the eye is evaluated by looking at the eye. If there is dysfunction in CN III ventrolateral strabismus will be seen. Often times, the affected eye has a dilated pupil.

A drooping eyelid (ptosis) indicates paralysis of the levator palpebrae muscle.