"The Cause" (part 1 of 3) Most people think that the shoulder is a ball and socket connection much like the hip joint; nothing could be further from the truth. The shoulder is made up of two main bones the humerus the large bone in the upper arm, and the scapula the fan shaped bone of the upper back. The humerus is covered by cartilage which in a cartilage covered semi cup called the glenoid. This and the top boney extensions of the scapula make up a very fragile ball joint. When its time to evaluate the shoulder muscles, most people we think of the shoulder muscles we think of the deltoids, and the trapezius. However the shoulder is made up of other lesser seen muscles whose development is essential to health shoulder joints. These lesser muscles are the Supraspinatus, Infraspinatus and the teres major, minor better know as the rotor cuff muscles. Below is the action of these muscles, there purpose, origin and insertions: Supraspinatus: This muscle has an origin at the top of the scapula and an insertion at the top or superior facet of the humerus. This muscle initiates and assists the deltoid in the abduction (rising) of the arm. Infraspinatus: this fan shaped muscle has it origin at the middle of the scapula it covers about 90 percent of the scapula and insert at Middle facet on greater tuberosity of humerus (the larger tube shape connection of the upper arm at the ball shaped top). The purpose of this muscle is to lateral lift the arm help to hold the humeral head in the glenoid cavity of the scapula Teres Major: this muscle has it origin at the lower inside of the scapula and insertion is at the middle of the opposite side of the humerus, just below the humeral head. The purpose of this muscle is to abduct and rotate the arm across the body, as if your elbow was pointing down and just your forearm rotated across your body. Teres Minor: This tiny muscle has its origin at the lateral boarder of the scapula just above the teres major, and its insertion at the Inferior facet on greater tuberosity of humerus. This little muscle has to lateral rotate the arm, and like the Infraspinatus help to hold the humeral head in the glenoid cavity of the scapula. Not only to the rotor cuff muscle stabilize the shoulder they assist in moving the arm especially during internal and external rotation. However the ability of the rotor cuff muscle to stabilize depends on their strength in relation to the larger deltoids and trapezius muscles. The solution to shoulder pain is simple strengthen the rotor cuff muscles and the shoulder pain goes away. But where did the pain come from in the beginning? Easy, when the humeral head of the upper arm is stretched in such a way that it separates form the glenoid cup, the rotor cuff muscles can no longer stabilize the shoulder. This would happen when doing stretching (I prescribe to the theory of never stretching the shoulder) or when an exercise that used the shoulder muscles are pulled from what I call an unnatural position (as in behind the neck pulldowns). There are only two other for working around this problem short of surgery, modify your workout so that you are less likely to injury the shoulder; or do exercises that can strengthen the stabilizer muscle of the rotor cuff. In this article I will address modifying the workout to prevent shoulder injury. Copyright Troy Caged Dog Pearsall
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