Role of the long head of the biceps brachii muscle in axial humeral rotation control.
There is still no consensus on the role of the tendon of the long head of the biceps (LHB) in providing shoulder stability. Further insight in its function can lead to improved understanding of shoulder pain, instability, ROM restriction patterns during rehabilitation and adjustment of indications for tenodesis. This study aimed to determine the rotational forces generated by tensioning of the LHB. Six cadaver specimens were prepared so that tensioning of the LHB and different degrees of glenohumeral elevation could be replicated.
It was found that loading of the LHB can either restrict or facilitate both internal and external rotation of the glenohumeral joint, depending on the degree of glenohumeral elevation. Below 10 degrees of elevation the LHB generates internal rotation and restricts external rotation; from 10 to 45 degrees of elevation this effect is reversed, and external rotation is facilitated, while tension in the LHB limits internal rotation.
Above 45 degrees of elevation both internal as well as external rotation become more restricted as tensioning of the LHB increases. Extreme rotations in an elevated arm position, such as overhead throwing, cause loading of the LHB and may therefore contribute to the development of injuries to the LHB or the biceps/ labrum complex > From Eshuis et al.; Clin Anat 25 (2012) 737-745. All rights reserved to Wiley Periodicals, Inc.
The Pubmed summary of the article can be found here.
The long head of the biceps tendon: partially intra capsular but extra articular.
Labral insertion of long head biceps.
