Stabilizers of the Shoulder
- muscular stabilizers
- static stabilizers
- stabilizers include: glenoid, glenoid labrum, negative intraarticular pressure, glenohumeral capsular ligaments, rotator cuff and scapular muscles;
- stabilizers include glenohumeral size, posteriorly angulated glenoid & humeral head, & functional muscle control (most important);
- structure that is most responsible for preventing anterior glenohumeral dislocation varies with the position of the arm.
- 0 deg: at 0 degrees of abduction, subscapularis muscle stabilizes the joint to a large extent.
- 45 deg: at 45 degrees of abduction subscapularis, middle glenohumeral ligament, and the anterior superior fibers of inferior glenohumeral ligament provide shoulder stability; (greatest strain in the inferior and middle ligaments);
- 90 deg: in abduction with external rotation, the inferior glenohumeral ligament prevents dislocation;
- when arm is in a position of anterior instability (90 deg abduction & 90 degrees external rotation), role of dynamic stabilizers changes.
- in this position, pectoral, short head of biceps, coracobrachial, anterior deltoid, & subscapularis resist anterior dislocation
Stabilizing mechanisms preventing anterior dislocation of the glenohumeral joint.
Original Text by Clifford R. Wheeless, III, MD.
Last updated by Data Trace Staff on Monday, June 25, 2012 3:14 pm