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3 Ta k e 5 a n d t r y A B M P F i v e - M i n u t e M u s c l e s a t w w w. a b m p . c o m / f i v e - m i n u t e - m u s c l e s . 97 vulnerable to chronic degeneration due to friction in the bicipital groove (Image 1). As the tendon of the long head of the biceps leaves its origin site on the supraglenoid tubercle, it courses under the acromion process on its way out of the shoulder joint capsule. As it leaves the capsule, it makes a sharp turn to head down the arm between the greater and lesser tubercles of the humerus. The groove between the two tubercles is called the bicipital or intertubercular groove. The long head tendon is exposed to significant friction as it makes the sharp turn over the top of the humerus to pass between the tuberosities. A synovial sheath envelops the tendon to reduce damaging friction on the tendon (Image 2). Most tendons surrounded by synovial sheaths are in the distal extremities where they have to bend across the foot and hand bones. The long head of the biceps is one of the few tendons in the body encased within a synovial sheath that is not in the distal extremities. DESCRIPTION OF PATHOLOGY There are two main conditions that could both be considered bicipital tendinopathy: tendinosis and tenosynovitis. Tendinosis involves collagen degeneration within the tendon, and tenosynovitis involves an inflammatory irritation and potential adhesion between the tendon and its surrounding synovial sheath. Tendinosis is now the preferred term for most chronic overuse tendon pathologies (as opposed to tendinitis). Histological examination has shown that there is minimal inflammatory activity with these conditions, so it is inappropriate to call the condition tendinitis. Tendinosis indicates some form of pathology in the tendon, although we are still learning more about what causes pain in this condition and how best to treat it. The tendon must be somewhat mobile within its synovial sheath so it can glide back and forth during elongation and contraction of the muscle and movements of the joint. Excess friction over the top of the humerus or in the groove can lead to irritation of the tendon within its sheath. This is a condition called tenosynovitis. Friction and pressure on the tendon fibers in this region can also produce the collagen degeneration of tendinosis. Having tendinosis and tenosynovitis present at the same time is possible. The symptoms of tenosynovitis are virtually the same as those of tendinosis, but luckily the two conditions are treated with the same approach, so making a specific distinction between them isn't crucial. Compression of soft tissues against the underside of the acromion process or under the coracoacromial ligament during shoulder motions is known as shoulder impingement. Subacromial impingement may be responsible for tendon degeneration in bicipital tendinosis as well. The biceps' long head tendon is especially susceptible to impingement at the end of shoulder flexion movements where the tendon is compressed against the coracoacromial arch (Image 3). Bicipital tendinosis is often secondary to impingement of other structures in the subacromial region of the shoulder. The biceps brachii is also the primary supinator of the forearm. Therefore, excessive supination, especially against resistance, may lead to the development of this condition. Excessive elbow flexion against resistance may do the same thing. These repetitive upper extremity motions occur in occupational, as well as recreational, settings with increasing frequency. Another possible cause of bicipital tendon dysfunction involves the movement of the tendon in the bicipital groove. The transverse humeral ligament spans between the greater and lesser tuberosities of the humerus and acts as a restraint to the tendon. Although the transverse humeral ligament holds the tendon in the groove, Compression of the biceps tendon under the coracoacromial arch. Image is from 3D4Medical's Complete Anatomy application. Tendon compressed under coracoacromial arch