Shoulder Actions and the Muscles Involved

 

The Shoulder Girdle

(movement of the entire shoulder girdle, scapular movement)

Muscles involved in movement

Action

Trapezius - upper fibers

elevate the scapula

Trapezius - middle fibers

elevate the scapula

upward rotation of the scapula

adduction of the scapula

Trapezius - lower fibers

depression of the scapula 

adduction of the scapula

upward rotation of the scapula

Levator Scapula

elevate the scapula 

downward rotation of the scapula

Rhomboids

adduction of the scapula

downward rotation of the scapula

elevate scapula

Serratus Anterior

abduction of the scapula

upward rotation of the scapula

Pectoralis Minor

abduction of the scapula

downward rotation of the scapula

depression of the scapula

 

The Shoulder Joint

(movement of the humerus in the glenohumeral joint)

 

Muscles involved in movement

Action

Deltoid - anterior fibers

abduction of the humerus/glenohumeral joint

flexion of the humerus/glenohumeral joint

horizontal adduction

internal rotation of the glenohumeral joint

Deltoid - middle fibers

abduction of the humerus/glenohumeral joint

Deltoid - lower fibers

abduction of the humerus/glenohumeral joint

extension of the humerus/glenohumeral joint

horizontal abduction of the humerus/glenohumeral joint

external rotation of the humerus/glenohumeral joint

Coracobrachialis

flexion of the humerus/glenohumeral joint

adduction of the humerus/glenohumeral joint

horizontal adduction of the humerous/glenohumeral joint

Supraspinatus

abduction of the humerus/glenohumeral joint

stabilization of the humeral head in the glenoid fossa

Infraspinatus

external rotation of the humerus/glenohumeral joint

horizontal adduction of the humerus/glenohumeral joint

stabilization of the humeral head in the glenoid fossa

Teres Minor

external rotation of the humerus/glenohumeral joint

horizontal abduction of the humerus/glenohumeral joint

extension of the humerus

stabilization of the humeral head in the glenoid fossa

Subscapularis

internal rotation of the glenohumeral joint

adduction of the humerus/glenohumeral joint

extension of the humerus

stabilization of the humeral head in the glenoid fossa

Teres Major

extension of the humerus

internal rotation of the glenohumeral joint

adduction of the humerus/glenohumeral joint

Latissimus Dorsi

extension of the humerus

internal rotation of the glenohumeral joint

adduction of the humerus/glenohumeral joint

horizontal abduction of the humerus/glenohumeral joint

Pectoralis Major - upper fibers

internal rotation of the glenohumeral joint

horizontal adduction

flexion of the humerus/glenohumeral joint

adduction of the humerus/glenohumeral joint

Pectoralis Major - lower fibers

internal rotation of the glenohumeral joint

horizontal adduction

extension of the humerus

addution of the humerus/glenohumeral joint