Which nerve innervates the flexor carpi ulnaris muscle?

• A. Median nerve
• B. Ulnar nerve
• C. Radial nerve
• D. Femoral nerve

Answer: (B)

The flexor carpi ulnaris muscle is primarily responsible for flexing and adducting the wrist. It plays a crucial role in movements that involve wrist and hand positioning, particularly when gripping and holding onto objects. The correct innervation of this muscle comes from the ulnar nerve.

The ulnar nerve branches off from the brachial plexus and specifically supplies the flexor carpi ulnaris along with a number of intrinsic muscles of the hand. Its role is significant in coordinating fine motor movements and providing sensation to the medial aspect of the hand. This targeted innervation is crucial for activities that require precision and control, especially those involving the ring and little fingers.

The median nerve, while it innervates several other forearm muscles, does not supply the flexor carpi ulnaris. Similarly, the radial nerve focuses on muscles that extend the wrist and fingers rather than those that flex it. The femoral nerve, on the other hand, is associated with the anterior thigh muscles and is not involved in innervating hand and wrist muscles at all. Therefore, the ulnar nerve is the correct answer, as it directly provides the necessary motor function to the flexor carpi ulnaris muscle.