- Arm (Front)
- Biceps Cubiti
- Long Head (Outer)
- Short Head (Inner)
- Flexion [1, 2 ]
- Supination [1, 2 ]
- Supraglenoid Tuberosity [1 ]
- Coracoid Process [2 ]
- Tubercle [1, 2 ]
- Fascia of forearm
- Bicipital Aponeurosis [1, 2 ]
The biceps brachii is a stronger elbow flexor when the radioulnar joint (forearm) is supinated. The biceps brachii is a stronger forearm supinator when the elbow is flexed.
During elbow flexion, motor units in the lateral portion of the long head of the biceps are preferentially activated, whereas during forearm rotation, motor units in the medial portion are preferentially activated (Ter Harr Romeny, et al. 1984).
During a dynamic elbow flexion, the biceps is more readily activated than the brachialis. Alternatively, the brachialis becomes more readily activated during isometric elbow flexion. (Tax et al., 1989)
The triarticulate biceps brachii muscles, particularly the short head [2 ] enters passive insufficiency through the completion of elbow extension when the shoulders are more extended or through the completion of shoulder extension when the elbows are more extended. The triarticulate biceps brachii muscles, particularly the short head [2 ] enters active insufficiency through the completion of elbow flexion when the shoulders are more flexed (brachialis becomes more active) or through the completion of shoulder flexion when the elbows are more flexed.