The biceps brachii short head originates from the coracoid alongside the coracobrachialis, forming a broad conjoined tendon before the two muscles diverge. The short head does not contribute to the long head's stability role at the shoulder — it functions primarily as an elbow flexor and forearm supinator. The short head is rarely injured in isolation; distal biceps ruptures at the radial tuberosity involve the combined tendon.
| Origin | Coracoid process tip alongside the coracobrachialis |
|---|---|
| Insertion | Radial tuberosity and bicipital aponeurosis (lacertus fibrosus) with the long head |
| Nerve Supply | Musculocutaneous nerve (C5, C6) |
| Blood Supply | Brachial artery |
| Actions | Supination of the forearm — the most powerful supinator; Flexion of the elbow; Flexion of the shoulder; Assists in horizontal adduction via coracoid origin |
|---|
Together with the long head it produces the powerful supination force needed to turn a screwdriver or open a jar. The two heads work synergistically for all elbow flexion and supination tasks, with the long head providing the additional shoulder stabilisation role.
Distal biceps tendon rupture at the radial tuberosity involves both heads and produces the pathognomonic Popeye deformity with elbow flexion and supination weakness. Surgical reattachment within 2 to 3 weeks restores supination strength to near-normal. Delayed repair produces permanent supination weakness of approximately 50 percent. The bicipital aponeurosis (lacertus fibrosus) can partially maintain elbow flexion even after complete tendon rupture.
The short head forms the medial portion of the biceps muscle belly, palpable along the medial aspect of the anterior arm when the two heads are distinguished during muscle contraction.
Combined short and long head avulsion from the radial tuberosity producing Popeye deformity, elbow flexion and supination weakness, managed with early surgical reattachment for optimal strength recovery.
