Introduction Function allows scapular motion against the rib cage Osteology not a true joint; actually an articulation between the scapula and the thorax is a sliding "joint" between medial border of scapula and ribs 2-7 resting position angulation (although these are variable even in healthy adults) anteriorly 10-20° internally rotated 30°-45° from the coronal plane upward tilt of 3° Biomechanics Motion primary motion elevation & depression login to view 1 more bullet secondary motions protraction & retraction login to view 1 more bullet upward & downward rotation login to view 2 more bullets internal & external rotation anterior & posterior tipping shoulder abduction the ratio of glenohumeral motion to scapulothoracic motion is 2:1 login to view 1 more bullet Stability 17 different muscles attach to or originate from the scapula trapezius serratus anterior deltoid latisimus dorsi levator scapulae rhomboid major rhomboid minor omohyoid - inferior belly pectoralis minor teres major teres minor triceps brachii biceps brachii coracobrachialis infraspinatus subscapularis supraspinatus Clinical Scapulothoracic dissociation Scapular winging Scapulothoracic dyskinesis