Which of the following muscles is innervated by the musculocutaneous nerve?

• A. Coracobrachialis
• B. Triceps brachii
• C. Flexor carpi radialis
• D. Extensor digitorum

Answer: (A)

The coracobrachialis muscle is indeed innervated by the musculocutaneous nerve, making it the correct choice. This nerve originates from the brachial plexus and is crucial for the sensation and movement of the arm. The coracobrachialis is primarily responsible for flexing and adducting the arm at the shoulder joint. Its innervation by the musculocutaneous nerve allows for precise movement and stabilization of the shoulder.

The other muscles listed are not innervated by the musculocutaneous nerve. The triceps brachii, which is involved in extending the elbow, is innervated by the radial nerve. The flexor carpi radialis, responsible for wrist flexion, is innervated by the median nerve. Lastly, the extensor digitorum, which extends the fingers, is also innervated by the radial nerve. This differentiation is key in understanding the functional anatomy of the upper limb.