Shoulder Biomechanics Mastery Course : Kinetics & Kinematics

Explore the shoulder complex, detailing four key structures: the sternoclavicular, acromioclavicular, scapulothoracic, and glenohumeral joints—and their bones and primary movements, with muscles driving flexion, abduction, rotation, and scapular motion.

Explore convex–concave rule in shoulder biomechanics, showing that when the convex surface moves, rolling and gliding occur in opposite directions, while when the concave surface moves, rolling and sliding align.

Explore how a muscle contracts from origin to insertion to move bones toward the insertion or origin, or pull both together, under brain control, knee flexion or posterior pelvic tilt.

Explore planes and axes of motion that describe shoulder movement, including the sagittal, frontal, and transverse planes and their axes of rotation, with oblique variations.

Examine the shoulder osteology, including the manubrium, clavicular facets, costal facets, and jugular notch. Analyze scapular borders, coracoid and acromion processes, and the glenohumeral joint alignment with the humeral head.

Examine the sternoclavicular joint, a saddle joint with convex-concave surfaces guiding clavicle motion. Coordinate elevation, depression, protraction, retraction, and axial rotation with scapulothoracic movement to enable shoulder function.

Explore the acromioclavicular joint, a gliding plane joint between the clavicle and acromion, with three degrees of freedom including upward and downward rotation to guide scapular motion and thorax alignment.

Explore the scapulothoracic joint as a pseudo joint where the scapula slides over the thorax, with the sternoclavicular and acromioclavicular joints coordinating elevation, depression, and rotations.

Explore the glenohumeral joint, where the humeral head articulates with the glenoid fossa and moves with the scapula through abduction, flexion/extension, rotation, and subacromial space via convex-concave rolling and sliding.

Explain the six kinematic principles of shoulder abduction, detailing the coordinated scapulohumeral rhythm, scapulothoracic and acromioclavicular joint actions that enable 180-degree abduction.

Explore the kinetics of the scapulothoracic and glenohumeral joints, detailing elevation and depression mechanics, key muscles, and implications for posture, crutch use, and tetraplegia.

Explore scapular protraction and retraction, with serratus anterior as the main retractor and rhomboids coordinating with the middle trapezius for pure retraction; protraction supports pushing, including push-up plus.

Explore how the glenohumeral and scapulothoracic joints coordinate shoulder elevation through flexion or abduction, upward rotation, and rotator cuff stabilization to protect the subacromial space.

Explore shoulder adductors and extensors, including the posterior deltoid and latissimus dorsi, as the arm moves from flexed abducted to anatomical position, with scapular stabilization.

Examine internal and external rotators, their torque differences, and how eccentric activation brakes external rotation to produce shear forces that affect humerus stability and scapular stabilization by the middle trapezius.