The third cranial nerve controls which functions?

The third cranial nerve controls which functions?

• A. Eye movements and pupil constriction
• B. Hearing and balance
• C. Facial sensation and mastication
• D. Taste and gag reflex

Answer: (A)

The third cranial nerve (oculomotor) is responsible for most eye movements, eyelid elevation, and pupil constriction. It innervates four extraocular muscles (superior, inferior, and medial rectus, plus inferior oblique) that move the eye, and the levator palpebrae superioris that raises the eyelid. It also carries parasympathetic fibers to the sphincter pupillae, which constricts the pupil, and to the ciliary muscle, which adjusts lens shape for near vision. This combination—controlling eye motion and adjusting the pupil and lens—fits the option describing eye movements and pupil constriction. Hearing and balance are handled by the vestibulocochlear nerve; facial sensation and chewing are functions of the trigeminal nerve; taste and gag reflex involve the facial, glossopharyngeal, and vagus nerves.

The third cranial nerve (oculomotor) is responsible for most eye movements, eyelid elevation, and pupil constriction. It innervates four extraocular muscles (superior, inferior, and medial rectus, plus inferior oblique) that move the eye, and the levator palpebrae superioris that raises the eyelid. It also carries parasympathetic fibers to the sphincter pupillae, which constricts the pupil, and to the ciliary muscle, which adjusts lens shape for near vision. This combination—controlling eye motion and adjusting the pupil and lens—fits the option describing eye movements and pupil constriction.

Hearing and balance are handled by the vestibulocochlear nerve; facial sensation and chewing are functions of the trigeminal nerve; taste and gag reflex involve the facial, glossopharyngeal, and vagus nerves.