Which of the following is NOT innervated by the musculocutaneous nerve?

• A. Biceps brachii
• B. Brachialis
• C. Coracobrachialis
• D. Flexor carpi ulnaris

Answer: (D)

The flexor carpi ulnaris is not innervated by the musculocutaneous nerve; instead, it is innervated by the ulnar nerve. This muscle is located in the forearm and plays a key role in wrist flexion and adduction.

In contrast, the biceps brachii, brachialis, and coracobrachialis are all innervated by the musculocutaneous nerve, which arises from the brachial plexus. The biceps brachii is primarily responsible for elbow flexion and supination of the forearm. The brachialis is also involved in elbow flexion, acting as a powerful flexor regardless of forearm position. The coracobrachialis assists in flexing and adducting the arm at the shoulder joint.

Understanding the specific innervations helps clarify the distinctions among these muscles, and recognizing the roles of the nerves involved is crucial for grasping both anatomy and clinical implications related to nerve damage or lesions.