Pages: 6 (1429 words) /
Published: Nov 10th, 2005
The most common dislocation after a severe trauma is a glenohumeral dislocation.
Overhead sports such as tennis, volleyball, and baseball are associated with glenohumeral instability. (2) These activities cause the joint to be in abduction and external rotation.
Repetition of motion, collision, or falling on an outstretched arm can lead to instability and/or dislocation. The Glenohumeral joint is already prone to dislocation, because of it being a large head of the humerus going into a relatively small socket. Almost ninety five percent of dislocations in the glenohumeral joint are anterior.(2)
The shoulders dynamic joint components provide the shoulder with the stability. The muscles and tendons form a cuff like arrangement around the joint.(2) The glenohumeral joint relies on support from a group of four muscles know as the rotator cuff. These muscles allow the shoulder to function, while maintaining balance between mobility and stability.(3) The rotator cuff allows the humeral head to stay within 1-2 millimeters of the middle of the glenoid fossa.(3) These muscles compress and depress the humeral head to prevent it from rolling off the top of the fossa.(3) More Specifically, the Supraspinatus works closely with the deltoid for arm flexion and abduction. The Supraspinatus comes from the Supraspinatus fossa of the scapula, and attaches to the greater tuberosity of the humeral head .(3)The subscapularis, is an internal rotator, and is found in the subscapular fossa, and then inserts on the lesser tuberosity.(3) The infraspinatus is found in the infraspinatus fossa on the posterior surface of the scapula, it also attaches to the greater tuberosity of the humerus.(3) The teres minor is another muscle, which attaches at the greater tuberosity, it along with the infraspinatus perform external rotation.(3) The rhomboids retract and rotates the scapula to depress the glenoid cavity inferiorly and fixes the scapula to the