injuries poisoning
Rotator Cuff Injury Subacromial Bursitis
Etiology of Rotator Cuff Injury
Rotator cuff injury can be an acute or chronic sports injury, but it commonly occurs for reasons unrelated to sports activities and in people with no history of overuse. A strain of the rotator cuff is a single acute, traumatic injury to the muscles. Tendinitis typically results from chronic impingement of the supraspinatus tendon between the humeral head and coracoacromial arch (the acromion, acromioclavicular joint, coracoid process, and coracoacromial ligament). Activities that require the arm to be moved over the head repeatedly, such as pitching in baseball, lifting heavy weights over the shoulder, serving the ball in racket sports, and swimming freestyle, butterfly, or backstroke, increase the risk. The supraspinatus tendon is thought to be particularly susceptible because it has an undervascularized region near its insertion on the greater tuberosity. The resultant inflammatory reaction and edema further narrow the subacromial space, accelerating tendon irritation or damage. If the process is not interrupted, the resulting inflammation can lead to partial or complete tear of the rotator cuff. Degenerative rotator cuff tendinitis is common among older (>40 years) adults who are not athletes for the same reason. Subacromial bursitis (inflammation, swelling, and fibrosis of the bursal area above the rotator cuff) commonly results from tendinitis of the cuff. 