Muscles are a very strong yet, delicate tool in our body. The help with movement, keeping bones in place, structure of the body, and they help every other body system do its job. I chose to focus on a group of muscles called the rotator cuff. The rotator cuff is a group of four muscles and tendons that attach to the shoulder joint, it allows the shoulder to move and keep stable. The names of the four muscles are the supraspinatus, infraspinatus, teres minor, and the subscapularis. Their job is to hold the head of the humerus into the scapula. Most rotator cuff injuries occur in people over 30 or atheletes in sports where the arm is moved over the head repeatedly, such as swimming, tennis, and baseball. Two main rotator cuff injuries are rotator cuff tendonitis and a rotator cuff tear. Rotator cuff tendonitis is an inflammation of one of the shoulder's tendons. A tear is ripping of one or mroe of its tendons. The muscles each can be torn and have different jobs, such as the supraspinatus, which is the major muscle of the shoulder joint, its main function is the abduction of the arm. The main functions of the subscapularis are the movement of the humerus, and elevation of the arm, which requires the depression of the humerus head. Both the infraspinatus and teres minor's main functions are to help with the lateral motion of the arm. SYMPTOMS Diagnosis of a rotator cuff injury are usually noticed during a physical examination. A magnetic resonance image (MRI) is the main procedure to detect tears of tendons. Other ways of examining tears are X-rays which are used to see the severity of the tear and to see if it is one or multiple tears. Arthograms, a test in which dye is injected into the shoulder joint and X-rays are taken to see where it leaks out indicating a tear, are also sometimes used but can cause pain afterwards. Most injuries can be noticed though because of increasing pain in the shoulder. After diagnosis of a tear