Final answer:
The musculocutaneous nerve pierces the coracobrachialis muscle and is part of the brachial plexus.
Step-by-step explanation:
The nerve that pierces the coracobrachialis muscle, which is known for its role in flexing and adducting the arm, is the musculocutaneous nerve. This nerve is part of the brachial plexus, which is associated with the lower cervical spinal nerves and the first thoracic spinal nerve. The musculocutaneous nerve originates from the brachial plexus and specifically innervates the muscles of the anterior compartment of the arm, including the biceps brachii, brachialis, and coracobrachialis.