Anatomy Trochlear nerve A Supplies the inferior oblique muscle of the eyeball B Is the only cranial nerve to emerge from the dorsal aspect of the brainstem C Has its nucleus of origin in the midbrain at the level of the superior colliculus D Enters the orbit through the middle compartment of the superior orbital fissure 💡 Explanation Trochlear nerve ✓ Correct Answer: B. Is the only cranial nerve to emerge from the dorsal aspect of the brainstem