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
Annular ligaments of fingers Annular ligaments of fingers In human anatomy, the annular ligaments of the fingers, often referred to as A pulleys, are the annular part of the fibrous sheathes of the fingers. Four or five such annular pulleys, together with three cruciate pulleys, form a fibro-osseous tunnel on the palmar aspect of the hand through which passes the deep and superficial flexor tendons. The annular and cruciate ligaments serve to govern the flexor mechanism of the hand and wrist, providing critical constraints to the flexor tendons to prevent bowstringing upon contraction and excursion of extrinsic flexor musculo-tendinous units. The first annular pulley