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
Collateral ligaments of metacarpophalangeal joints while the proper ligaments are shortened. As a result, the joint is stable during full flexion while the relaxed collateral ligaments allows lateral and rotation movements during extension. The tendons of interosseous and lumbricales add to the lateral stability of the joint. Collateral ligaments of metacarpophalangeal joints In human anatomy, the radial (RCL) and ulnar (UCL) collateral ligaments of the metacarpophalangeal joints (MCP) of the hand are the primary stabilisers of the MCP joints. They have two parts: the cord-like collateral ligaments proper located more dorsally and the accessory collateral ligaments located more volarly. They enable us to spread our