Which of the following muscles is NOT innervated by the radial nerve?

• A. Triceps
• B. Brachialis
• C. Flexor carpi radialis
• D. Lateral digital extensor

Answer: (C)

The flexor carpi radialis is not innervated by the radial nerve; instead, it is innervated by the median nerve. The flexor carpi radialis is primarily involved in wrist flexion and abduction, which requires median nerve activation.

In contrast, the triceps brachii, which extends the elbow, is indeed innervated by the radial nerve. The brachialis, another muscle involved in elbow flexion, is primarily innervated by the musculocutaneous nerve. However, it also receives some contribution from the radial nerve, especially in its lateral part. The lateral digital extensor is a muscle of the forearm that aids in the extension of the fingers and is specifically innervated by the radial nerve as well.

Identifying the innervation helps clarify the functional roles of these muscles and their contributions to movements. Understanding these distinctions is crucial for applications in anatomy and clinical settings where muscle function and nerve damage may be involved.