There is still disagreement regarding the functions of the long head of the biceps brachii muscle. It has been described as a stabilizer of the humeral head in the glenoid, preventing superior translation during abduction;2 an anterior and posterior stabilizer; a limiter of external rotation; a lifter of the glenoid labrum; and a shoulder head compressor, among other things.1 Perry stated that in the throwing position, the biceps was more important as an elbow muscle than as a significant stabilizing force at the glenohumeral joint.3 In throwing, the biceps functions principally as an elbow decelerator. The problem with some of these studies is that when these functions were tested, bicipital activity at the elbow was allowed and shoulder activity was not isolated. So, was the activity of the long head due to the elbow or the shoulder movement?
The actual function of the long head of the biceps remains debatable. Pure traction overload tendinitis of the biceps tendon has not been identified, although few investigators have performed actual biopsy studies of the bicipital tendon at the time of treatment.4 Some surgeons even regard it as a vestigial structure and when symptomatic, have excised it or anchored the tendon to prevent it from moving (tenodesis). Actually, the brachialis is the prime elbow flexor. Yamaguchi, et al.,5, braced the elbow at 100 degrees, and in checking shoulder motion, found no isolated bicipital activity in weighted and rapid shoulder motions. More recently, Levy, et al.,1 demonstrated that the long head of the biceps was not active in isolated shoulder motion when the elbow and forearm were controlled, and that bicipital function correlated with motion at the elbow, not the shoulder. They stated, "Any function attributed to the long head of the biceps is achieved by either a passive role (i.e., proprioception) of the tendon or an active role that achieves tension in association with elbow and forearm activity."
As I think now about shoulder cases, I realize that I rarely treat the long head.
- Levy AS, Kelly BT, Lintner SA, et al. Function of the long head of the biceps at the shoulder: electromyographic analysis. J Shoulder Elbow Surg 2001;10 (3):250-255.
- Warner JJ, McMahon PJ. The role of the long head of the biceps brachii in superior stability of the glenohumeral joint. J Bone Joint Surg Am 1995;77:366-372
- Perry J. Biomechanics of theshoulder. In: Rowe CR, ed. The Shoulder. New York: Churchill Livingstone, 1988:17-33.
- Wolf WB. Shoulder tendinosis. Clin Sports Med 1992;11(4):871-890.
- Yamaguchi K, Riew DK, Galatz IM et al. Biceps activity during shoulder motion: an electromyographic analysis. Clin Orthop 1997;336:122-9.
Warren Hammer, MS, DC, DABCO
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