Final answer:
The biceps brachii, brachialis, and brachioradialis are located in the anterior flexor compartment of the arm, responsible for flexing the forearm, while their antagonist, the triceps brachii, is located in the posterior compartment of the arm and is responsible for extending the forearm.
Step-by-step explanation:
The biceps brachii, brachialis, and brachioradialis make up the anterior compartment of the arm, specifically labeled as the anterior flexor compartment of the arm. These muscles are primarily responsible for flexing the forearm. The antagonist muscles to these are commonly the muscles in the posterior compartment of the arm, which includes the triceps brachii, mainly responsible for extending the forearm. The triceps brachii muscle is located in what is known as the posterior compartment of the arm, which works in opposition to the anterior compartment muscles during forearm movement.
Explanation of Muscle Action
When you bend your arm, the biceps brachii contracts and the triceps brachii relaxes; when you straighten your arm, the triceps brachii contracts and the biceps brachii relaxes. This process exemplifies how skeletal muscles often work in opposing pairs due to their ability to only pull, not push. This is essential for the coordinated movement of the joints they span.