Trapezius (Upper fibers) O: base of skull, occipital protuberance, posterior ligaments of neck I: posterior aspect of lateral 1/3 of clavicle A: elevation of scapula, extension and rotation of head at the neck

Trapezius (Middle fibers) O: spinous processes of 7th cervical and upper three thoracic vertebrae I: medial border of acromion process and upper border of scapular spine A: elevation, upward rotation, and adduction (retraction) of scapula

Trapezius (Lower fibers) O: spinous process of 4 th through 12 th thoracic vertebrae I: triangular space at the base of scapular spine A: depression, adduction (retraction), and upward rotation of scapula

Levator scapulae O: Transverse processes of upper four cervical vertebrae I: Medial border of scapula above base of scapular spine A: Elevates the medial margin of scapula, weak downward rotation and weak adduction

Rhomboid minor and major O: Spinous processes of last cervical and first five thoracic vertebrae I: Medial border of scapula below the spine A: Acting together: adduction (retraction) of scapula, rotation downward from upward rotated position, and elevation

Serratus anterior O: Surface of upper nine ribs at side of chest I: Anterior aspect of whole length of medial border of scapula A: Abduction (protraction) and rotation upward of scapula

Pectoralis minor O: Anterior surfaces of 3 rd to 5 th ribs I: Coracoid process of scapula A: Abduction (protraction) of scapula, downward rotation of scapula, and depression of scapula from elevated position

Subclavius O: Superior aspect of 1 st rib at its junction with its costal cartilage I: Inferior groove in the midportion of clavicle A: Stabilization and protection of sternoclavicular joint, depression and abduction of scapula

Joints of the Shoulder Glenohumeral Joint Acromioclavicular Joint Coracoclavicular joint Sternoclavicular joint Coracoacromial joint

Ligaments of the Shoulder Coracohumeral ligament – stabilizes the superior part of glenohumeral joint Glenohumeral ligament (superior, middle, inferior) – stabilizes the anterior part of the glenohumeral joint Transverse humeral ligament – stabilizes the biceps brachii tendon (long head) Coracoacromial ligament (coracoacromial arch) – stabilizes the superior part of glenohumeral joint Acromioclavicular ligament - stabilizes the acromioclavicular joint (AC joint)

Coracohumeral and Glenohumeral Ligaments (superior, middle, inferior)

Transverse humeral ligament

Coracoacromial Arch (acromion, coracoid process, coracoacromial ligament)

Acromioclavicular Ligament