Test: Cranial Nerve IV exam

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Background/Purpose

Procedure

The trochlear nerve, cranial nerve IV, is a motor nerve that innervates the superior oblique muscle of the eye, which operates through the pulley-like trochlea to move the eye on the opposite side (contralateral) from its origin where it depresses and abducts the eyeball. It is synergistic with the extraocular muscles and is tested by asking the patient to look 'down and in' as the contribution of the superior oblique is greatest in this motion. Diplopia associated with these activities may be the initial symptom of a fourth nerve palsy.
Performed: Bilaterally

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Trochlear nerve exam

Criteria

• Able to look down and in
• No nystagmus or strabismus

Measurement

0.00

LOINC Code

0

Scale/Grading

Pass/Fail