Which muscle is innervated by the musculocutaneous nerve?

The coracobrachialis muscle is indeed innervated by the musculocutaneous nerve. This nerve arises from the brachial plexus and primarily innervates the muscles in the anterior compartment of the arm. The coracobrachialis plays a critical role in flexing and adducting the shoulder joint, and its position deep to the biceps brachii makes it an important muscle for overhead motions and lifting.

The other muscles mentioned in the options are innervated by different nerves. For instance, the deltoid muscle is primarily innervated by the axillary nerve, while the triceps brachii is innervated by the radial nerve. The supraspinatus, another important shoulder muscle, receives its innervation from the suprascapular nerve. Understanding the innervation of these muscles helps clarify their functional roles and the pathways involved in motor control of the upper limb.