Which nerve innervates the flexor carpi ulnaris?

The flexor carpi ulnaris muscle is primarily responsible for the flexion and adduction of the wrist. Its innervation is specifically provided by the ulnar nerve. This nerve arises from the medial cord of the brachial plexus and travels down the arm, passing behind the medial epicondyle of the humerus at the elbow.

The ulnar nerve's trajectory places it in close proximity to the flexor carpi ulnaris, allowing it to effectively stimulate this muscle to contract. In practical terms, when you need to perform actions involving wrist flexion and adduction, it is the ulnar nerve that sends the necessary signals to the flexor carpi ulnaris to carry out those movements.

Other nerves listed, such as the median nerve, provide innervation to other muscles in the forearm responsible for different functions, while the radial nerve mainly innervates extensors, and the brachial nerve is not a specific nerve but rather a network from which other nerves branch out. Hence, recognizing the specific role of the ulnar nerve in innervating the flexor carpi ulnaris is crucial for understanding wrist movements and muscle functions in the forearm.