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Evaluation and Treatment of Rotator Cuff Impairments: Summary
Infraspinatus and Teres Minor The infraspinatus and teres minor both control external rotation of the shoulder. These muscles arise from the back of the scapula and insert into the humerus, playing a role in movements like throwing and reaching behind the body. They also help stabilize the shoulder joint, preventing the humeral head from shifting too far during rotation. Subscapularis The subscapularis is the largest rotator cuff muscle and is responsible for internal rotation of the shoulder. Located on the front of the scapula, it stabilizes the anterior part of the shoulder. Tightness in this muscle can limit shoulder flexion and lead to postural issues such as a forward shoulder posture or internally rotated shoulders. Common Injuries and Dysfunction Rotator cuff injuries are typically caused by repetitive strain, trauma, or degenerative changes. These injuries can lead to pain, reduced range of motion, and muscle weakness. Some examples include the following: Impingement Impingement is a general term for disruption of tissue that can occur against multiple structures in numerous planes. Athletes and manual laborers who perform repetitive overhead movements are particularly at risk for impingement. Rotator Cuff Tears Rotator cuff tears can vary from partial to fullthickness, with the supraspinatus tendon being the most commonly affected. Tears often result from overuse or degenerative changes but can also be caused by trauma. Large tears can severely limit shoulder movement and make everyday tasks painful and difficult. Tendinopathy Tendinopathy involves the chronic degeneration of rotator cuff tendons, often caused by overuse. As this degeneration progresses, it can lead to pain, weakness, and a reduction in shoulder function. A key concept in understanding how the behavior of muscles, tendons, and tissues over time can lead to tendinopathy is plasticity. While muscles are primarily elastic, meaning they return to their original shape after being stretched, they can also exhibit plasticity—a property where tissues maintain a new shape after being stretched or deformed for long periods. For example, when muscles are kept in shortened positions for prolonged periods, like when sitting for long hours, they might not fully return to their original length. This is why muscle imbalances can develop, and why corrective exercises, particularly stretching, are effective in gradually restoring muscle length.
LEARNING TIP! The acromion process, which acts as the “peak” of the scapula, helps determine which way the scapula is rotating. This rotational motion is crucial for maintaining proper alignment of the humerus and scapula, which prevents impingement as well as decreased strength and range of motion, and it keeps the shoulder functioning properly.
Translational and rotational movements work in harmony to keep the shoulder joint stable and functioning efficiently. For instance, when you raise your arm, the scapula not only rotates upward but also elevates and protracts slightly, allowing for full range of motion. EVIDENCE-BASED PRACTICE Standing in anatomical position, the scapula is naturally oriented slightly upward and forward, around 30 to 35 degrees anterior to the frontal plan, a position that supports optimal shoulder function and helps prevent issues like impingement . To become more aware of the movement mechanics in the shoulder girdle, particularly how the clavicle and scapula contribute to shoulder mobility, try the following exercise: 1. Put your right index finger on your left clavicle. 2. Slowly move your left arm into shoulder flexion. 3. Can you feel the clavicle moving? 4. Locate the acromion process. 5. Abduct your humerus. 6. Can you feel the scapula rotating THE ROTATOR CUFF The rotator cuff is a group of four muscles, the supraspinatus, infraspinatus, teres minor, and subscapularis, that are essential for stabilizing the shoulder joint. They work together to keep the humeral head centered in the coracoacromial arch during movement. Without this stabilization, the shoulder would be at risk for dislocation or impingement . Supraspinatus The supraspinatus is a relatively small muscle that is crucial for initiating arm abduction, handling the first 15 degrees before the deltoid takes over. Located at the top of the scapula, it is often vulnerable to injury due to its position under the acromion, where impingement can easily occur if shoulder mechanics are off.
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