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 males than in females within the ages of 50–60 years old, within the ages of 70–80 years old there wasn’t much difference in prevalence. The data of this study showed that the prevalence of a rotator cuff tear in the general population is 22.1% Yamamoto et al. performed a medical examination on 683 people whom live in a mountain village. The purpose of this study was to determine the prevalence of a rotator cuff tear among a population. Yamamoto found that among the mountain village population, rotator cuff tears were present in 20.7% of the village population. In both of