The trochlear nerve innervates which muscle?

The trochlear nerve innervates which muscle?

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

Answer: (A)

The fourth cranial nerve feeds the superior oblique muscle. This muscle's job is to depress the eye when it is looking inward (adducted) and to intort the eye as it moves, with its tendon passing through the trochlear pulley to redirect its pull. That unique path through the trochlea explains why this nerve is dedicated to this particular muscle. The other eyes’ muscles are controlled by other nerves—the medial rectus and inferior oblique by the oculomotor nerve, and the lateral rectus by the abducens nerve—so the superior oblique is the one innervated by the trochlear nerve.

The fourth cranial nerve feeds the superior oblique muscle. This muscle's job is to depress the eye when it is looking inward (adducted) and to intort the eye as it moves, with its tendon passing through the trochlear pulley to redirect its pull. That unique path through the trochlea explains why this nerve is dedicated to this particular muscle. The other eyes’ muscles are controlled by other nerves—the medial rectus and inferior oblique by the oculomotor nerve, and the lateral rectus by the abducens nerve—so the superior oblique is the one innervated by the trochlear nerve.