Which cranial nerves are tested when a clinician asks a patient to visually follow a finger through the cardinal fields of gaze?

Which cranial nerves are tested when a clinician asks a patient to visually follow a finger through the cardinal fields of gaze?

• A. I, II, IV
• B. III, IV, VI
• C. II, III, IV
• D. V, VI, VII

Answer: (B)

Conjugate eye movements tested by following a moving finger through the cardinal gaze fields rely on the cranial nerves that innervate the extraocular muscles. The nerves responsible are the third (oculomotor), the fourth (trochlear), and the sixth (abducens). They coordinate the muscles that move the eye in all directions: the oculomotor nerve supplies most of the eye muscles (and the levator palpebrae), the trochlear nerve innervates the superior oblique, and the abducens nerve innervates the lateral rectus. The optic nerve (second) handles vision itself, not eye movement, so it isn’t assessed with this movement test. If a problem emerges in a particular direction of gaze, it localizes to the nerve that moves the corresponding eye muscle (for example, inability to abduct points to the sixth nerve).

Conjugate eye movements tested by following a moving finger through the cardinal gaze fields rely on the cranial nerves that innervate the extraocular muscles. The nerves responsible are the third (oculomotor), the fourth (trochlear), and the sixth (abducens). They coordinate the muscles that move the eye in all directions: the oculomotor nerve supplies most of the eye muscles (and the levator palpebrae), the trochlear nerve innervates the superior oblique, and the abducens nerve innervates the lateral rectus. The optic nerve (second) handles vision itself, not eye movement, so it isn’t assessed with this movement test. If a problem emerges in a particular direction of gaze, it localizes to the nerve that moves the corresponding eye muscle (for example, inability to abduct points to the sixth nerve).