Biceps brachii muscle
A guy straining his biceps.
In human anatomy, biceps brachii is a muscle on the upper arm that acts to flex the elbow. It is arguably the best known muscle, as it lies fairly superficially, and is often well-defined even in non-athletes.
It is given the name biceps because it has two heads, and brachii comes from the Latin word for arm.
Distally, biceps attaches to the radial tuberosity, and because this bone can rotate, the biceps also supinates the forearm. The biceps also connects with the fascia of the medial side of the arm, at the bicipital aponeurosis.
Proximally, the short head of biceps attaches to the coracoid process of the scapula. The tendon of the long head passes into the joint capsule at the head of the humerus, and attaches on the scapula at the supraglenoid tubercle.
