long head of biceps brachii

Origin at the supraglenoid tubercle, just above the shoulder joint, distinguishes the long head of biceps brachii from its short head. Its tendon passes down along the intertubercular groove of the humerus and into the joint capsule of the shoulder, so the tendon runs an intra-articular course before entering the arm. While the humerus is in motion, the greater and lesser tubercles together with the overlying transverse humeral ligament hold the tendon firmly within the groove. During movement from external to internal rotation the tendon is forced medially against the lesser tubercle and superiorly against the transverse ligament, so the restraints that stabilise it also bear load against it through the rotational range.