Upper Extremity Musculature

Shoulder Complex Scapula Clacivle Sternum Humerus Rib Cage Sternoclavicular Joint Acromioclavicular Joint Glenohumeral Joint Scapulothoracic Joint / Articulation

Shoulder Girdle Motions available at the shoulder girdle are upward rotation, protraction, downward rotation, retraction, and scapular tilt (when the shoulder enters hyperextension) Scapulohumeral rhythm: The first 30 degrees of shoulder joint motion is pure GH motion. After the initial 30 degrees, for every 2 degrees of shoulder flexion or abduction, the scapula must upwardly rotate 1 degree. This results in a 2:1 ratio.

Scapulothoracic Joint Articulation of scapula with thorax Not a true joint Muscles associated with ST Joint (shoulder girdle) Trapezius Rhomboid Major Rhomboid Minor Levator Scapulae Serratus Anterior Pectoralis Minor

Trapezius

Upper Trapezius Origin Occipital Bone, nuchal ligament on cervical spinous processes Insertion Lateral third of clavicle, acromion process Action Scapular elevation and upward rotation Innervation Spinal accessory (cranial nerve XI), C3-C4 sensory component

Middle Trapezius Origin Spinous processes of C7 through T3 Insertion Scapular spine Action Scapular retraction Innervation Spinal accessory ( cranial nerve XI), C3 and C4 sensory component

Lower Trapezius Origin Spinous processes of middle and lower thoracic vertebrae Insertion Base of the scapular spine Action Scapular depression and upward rotation Innervation Spinal accessory ( cranial nerve XI), C3 and C4 sensory component

Rhomboid Major & Minor

Rhomboids Origin Spinous processes of C7 through T5 Insertion Medial border of scapula from level of spine to inferior angle Action Scapular retraction, elevation and downward rotation Innervation Dorsal scapular nerve (C5)

Levator Scapulae

Levator Scapulae Origin Transverse processes of C1 - C4 vertebrae Insertion Vertebral border of scapula between the superior angle and spine Action Scapular elevation and downward rotation Innervation Third and fourth cervical nerves and dorsal scapular nerve (C5)

Serratus Anterior

Serratus Anterior Origin Superolateral surfaces of upper 8 or 9 ribs at the side of chest Insertion Vertebral border of scapula, anterior surface Action Scapular protraction and upward rotation Innervation Long thoracic nerve (C5, C6, C7)

Pectoralis Minor

Pectoralis Minor Origin 3rd to 5th ribs, anterior surface Insertion Coracoid process of the scapula Action Scapular depression, protraction, downward rotation, and tilt Innervation Medial pectoral nerve (C8, T1)