CN III is associated with which function?

• A. Vision
• B. Movement of the tongue
• C. Eye movement and pupil response
• D. Facial sensation

Answer: (C)

The option referring to CN III, also known as the oculomotor nerve, is associated with eye movement and pupil response. This cranial nerve plays a crucial role in several ocular functions, including controlling the majority of the eye's movements. It innervates most of the extraocular muscles, which are responsible for moving the eyeball in various directions. Additionally, CN III is key in controlling the constriction of the pupil and the elevation of the eyelid.

Understanding the functions of the cranial nerves is fundamental, as each has a specific role related to sensory or motor functions throughout the body. In this case, while vision is related to the optic nerve (CN II), movement of the tongue is controlled by the hypoglossal nerve (CN XII), and facial sensation is associated with the trigeminal nerve (CN V). The primary role of CN III distinctly aligns with the movements of the eyes and the regulation of pupil size, making eye movement and pupil response the correct association.