Before revision: The trochlear nerve (), also called the fourth cranial nerve or CN IV, is a motor nerve (a somatic efferent nerve) that innervates only a single muscle: the superior oblique muscle of the eye, which operates through the pulley-like trochlea.
After revision: The trochlear nerve (), also called the fourth cranial nerve or CN IV, is a motor nerve (a somatic efferent nerve) that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pulley-like trochlea.