muscle Actions/OI

Trapezius O/I

origin: superior nuchal line, external occupational protuberance, sp C7-T12

Insertion: lateral clavicle, acromion process, & spine of scapula

Action: elevates, retracts, depresses scapula and can extend neck

Levator scapulae O/I

origin: tp c1-c4

Insertion: medial aspect of superior boarder of scapula

Action: elevation of scapula

Rhomboid major O/I

Sp-t2-T5

Insertion: medial boarder of scapula from spine to inferior angle

Action: retraction of scapula

Rhomboid minor O/I

Sp C7-T1

Insertion: medial boarder of scapula near spine of scapula

Action: retraction of scapula

Pectoralis minor O/I

Origin: anterior surface ribs 3-5

Insertion: coracoid process of scapula

Action: pulls scapula anteriorly & inferiorly ( protracts & depresses scapula)

Serratus anterior O/I

Origin: anterior lateral ribs 1-9

Insertion: anterior surface of medial boarder of scapula

Action: protracts scapula

Deltoid

Origin: clavicle & acromion and spine of scapula

Insertion: deltoid tuberosity of humerus

Actions: abducts shoulder joint, also can flex or extend at shoulder

Latissimus dorsi

Origin: spinous process of lower thoracic vertebrae and lower ribs

Insertion: intertubercular groove of humerus

Actions: flexes, adducts, and medially rotates shoulder

Pectoralis major

Origin: sternum, clavicle, and costal cartilage of ribs 2-6

Insertion: greater tubercle of humerus

Actions: flexes, adducts, and medially rotates shoulder