Also known by the Latin name biceps brachii (meaning "two-headed muscle of the arm"), the muscle's primary function is to flex the elbow and rotate the forearm. The heads of the muscle arise from the scapula (shoulder blade) and combine in the middle arm to form a muscle mass.

Bicep pain can have many different causes. These include biceps tendinitis, brachial plexus injury, and fractures. Symptoms include pain in the upper arm and elbow area and sometimes can radiate to the forearm. Some people experience swelling or limited movement.

A fifth muscle, the long head of biceps, while not technically part of the rotator cuff, also plays a major role. Muscles attach to bones via a tendon; the rotator cuff tendons all attach at the front shoulder on the upper arm bone called the humerus.

The biceps brachii (BB), commonly know as the biceps, is a large, thick muscle on the ventral portion of the upper arm. The muscle is composed of a short head and a long head. The long head is located on the lateral side of the biceps brachii while the short head is located on the medial side.