Architectural gear ratio and their accompanying tendons. These muscles form a cuff around the glenohumeral joint and function to stabilize and manipulate the shoulder. The pennation angle of the rotator cuff myofibers, the angle at which fibers connect to the associated tendon, affects the contractile properties and function of the whole pennate muscle. For example, the pennation angle determines the architectural gear ratio at which a pennate muscle operates. A large initial pennation angle results in a large AGR and velocity amplification. A 2011 study on human cadaveric shoulders suggests tendon tears may affect the pennation angle of the rotator cuff muscles. Researchers
Rotator cuff tear cuff is made up of the supraspinatus, infraspinatus, teres minor, and subscapularis. The supraspinatus is the most commonly affected. Treatment may include pain medication such as NSAIDs and specific exercises. It is recommended that people who are unable to raise their arm above 90 degrees after 2 weeks should be further assessed. In severe cases surgery may be indicted. Rotator cuff tears are common. Those over the age of 40 are most often affected. The condition has been described since at least the early 1800s. Many rotator cuff tears have no symptoms. Both partial and full thickness tears have been