The coracobrachialis tendon originates from the apex of the coracoid process, sharing this origin with the short head of the biceps brachii. The conjoined tendon of coracobrachialis and biceps short head is a consistent anatomical structure before the muscle fibres diverge. Coracobrachialis inserts via a flat tendon on the middle third of the medial surface of the humerus, at the level of the deltoid insertion.
The musculocutaneous nerve pierces the coracobrachialis muscle belly in most individuals, making coracobrachialis a key landmark for musculocutaneous nerve identification. During coracoplasty or subcoracoid decompression surgery, the conjoined tendon attachment to the coracoid is carefully preserved. Coracoid impingement syndrome involves compression of the subscapularis and conjoined tendon between the coracoid and the lesser tuberosity, producing anterior shoulder pain aggravated by horizontal adduction and internal rotation.
Compression of the coracobrachialis and biceps short head tendons, along with the subscapularis, between the coracoid tip and the lesser tuberosity during flexion and internal rotation, producing anterior shoulder pain managed with injection, physiotherapy, or arthroscopic coracoplasty.
Muscle or tendon strain from resisted arm adduction against resistance, uncommon but producing anterior shoulder and proximal medial upper arm pain with tenderness at the coracoid origin, managed conservatively.
