Trochlear nerve function involves movement of which extraocular muscle?

Trochlear nerve function involves movement of which extraocular muscle?

• A. Medial rectus
• B. Inferior oblique
• C. Superior oblique
• D. Lateral rectus

Answer: (C)

The trochlear nerve innervates the superior oblique muscle. This muscle’s role is to depress and intort the eye, with its downward-depressing action being most evident when the eye is adducted (turned toward the nose). That linkage—trochlear nerve → superior oblique → downward movement when the eye is adducted—is why this muscle is the correct answer. The medial rectus and inferior oblique are controlled by the oculomotor nerve, and the lateral rectus by the abducens nerve, which is why they aren’t associated with the trochlear nerve.

The trochlear nerve innervates the superior oblique muscle. This muscle’s role is to depress and intort the eye, with its downward-depressing action being most evident when the eye is adducted (turned toward the nose). That linkage—trochlear nerve → superior oblique → downward movement when the eye is adducted—is why this muscle is the correct answer. The medial rectus and inferior oblique are controlled by the oculomotor nerve, and the lateral rectus by the abducens nerve, which is why they aren’t associated with the trochlear nerve.