Which nerve is responsible for the innervation of the palmaris longus?

The palmaris longus muscle is primarily innervated by the median nerve. This nerve is crucial for motor function in the forearm and hand, particularly in flexing the wrist and aiding in the movement of the fingers. The palmaris longus, although somewhat variable in its presence among individuals, serves an important role in contributing to the palmar fascia, which supports grip.

In the context of the other choices, the ulnar nerve primarily innervates the intrinsic muscles of the hand and the flexor carpi ulnaris in the forearm, but not the palmaris longus. The radial nerve mainly innervates the extensor muscles of the forearm and does not have a role in the innervation of the palmaris longus. The musculocutaneous nerve is involved with the innervation of the anterior compartment of the arm, particularly the biceps brachii and brachialis, but it does not innervate the palmaris longus either. Therefore, the median nerve is correctly identified as the nerve responsible for the motor innervation of the palmaris longus.