Biceps Brachii Muscle (Long Head)

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The long head of the biceps brachii muscle is the larger of the two muscle bodies that forms the entire biceps brachii muscle. The biceps brachii gets its name from the Latin words for "two-headed" and "arm" which describe its structure and location. The long and short heads of the biceps brachii work together to achieve the same functions.

The long head extends from its origin on the superglenoid tubercle of the scapula and passes over the head of the humerus before merging with the short head. From the merger point, the entire muscle continues beyond the distal end of the humerus and inserts on the radial tuberosity of the radius.

Together with the short head, the long head of the biceps brachii acts as a flexor of the arm at the elbow joint and a supinator of the forearm. The biceps brachii, brachialis, and brachioradialis muscles all act as flexors of the arm at the elbow, with the brachialis acting as the agonist and the biceps brachii and brachioradialis acting as synergists. At the radioulnar joint in the forearm, the biceps brachii acts as a supinator to turn the palm of the hand upwards.