Final answer:
The musculocutaneous nerve innervates the biceps brachii, brachialis, and coracobrachialis, which are involved in forearm flexion and, for the biceps brachii, arm flexion at the shoulder and forearm supination.
Step-by-step explanation:
The muscles innervated by the musculocutaneous nerve include the biceps brachii, brachialis, and coracobrachialis. These muscles are primarily responsible for flexing the forearm.
The biceps brachii, in addition, assists with supinating the forearm and flexing the arm at the shoulder.
Deep to the biceps brachii, the brachialis provides additional power in flexing the forearm.
Together, these muscles form the anterior compartment of the arm, also known as the anterior flexor compartment of the arm.