In addition to the ulnar nerve, which nerve is primarily responsible for the function of the thumb and index finger?

The median nerve is primarily responsible for the function of the thumb and index finger. It plays a crucial role in the sensation and motor functions of these digits, particularly in the opposition of the thumb, which is essential for grasping and pinching objects. The median nerve innervates the muscles located in the thenar eminence, which includes the abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis, facilitating the movement of the thumb.

Additionally, the median nerve provides sensory innervation to the palmar side of the thumb, index finger, middle finger, and part of the ring finger. This makes it vital for fine motor skills and the ability to perform tasks that require precision.

When considering the other nerves listed, the radial nerve primarily serves the posterior aspect of the arm and forearm, focusing on wrist and finger extension. The musculocutaneous nerve primarily innervates the flexor muscles of the forearm, while the axillary nerve mainly supplies the deltoid and teres minor muscles in the shoulder. None of these options have the specialized role in thumb and index finger function that the median nerve possesses.