Shoulder Joint Anatomy - Section 2
The shoulder joint is one of the body's most flexible and mobile joints, allowing the arm to be positioned and moved in almost any direction.

In addition, the shoulder joint allows the arm to be rotated inward (internal rotation) or outward (external rotation) to help place the flexed forearm in a better position to accomplish any given task.

The head of the humerus, also called the humeral head, is almost spherical in shape and rotates freely in the glenoid fossa of the scapula. The shoulder joint's flexible ligaments, the rotator cuff, and the other muscles that cross this joint all add to the shoulder's stability and its extraordinary range of motion.
The dorsal or back side of the scapula contains two major areas - one is located above and one is located below the scapular spine. The area above the spine is called the supraspinatus fossa and serves as the origin for the supraspinatus muscle. The large area below the spine is termed the infraspinatus fossa; it serves as the origin for the infraspinatus muscle.
Like the subscapularis muscle, both of these posterior-based muscles insert on the humerus through the strong rotator cuff, and serve to stabilize the shoulder joint. The rotator cuff is the anatomical confluence of these three muscles as they attach to the head of the humerus.

This cuff, sometimes mistakenly called rotator "CUP" by patients, is one of the most important stabilizers of the shoulder joint. Any problem with this tendinous cuff may severely limit such activities as raising your arm above your head, reaching behind you, or doing forceful lifting. Continuing with sports-related activities or aggressive workouts may increase your risk of developing further problems.
Continue with Shoulder Joint Anatomy - Section Three