Upper Extremity Muscles

Major muscles and their actions. From 6.2 in the muscle reading

Anterior Deltoid

Structure: Front of the shoulder

Function and horizontal adduction

Middle Deltoid

Structure: middle shoulder

Function: Abduction

Posterior Deltoid

Structure: back of the shoulder. Function: extension and horizontal abduction.

Pectoralis Major 

Structure: chest muscle. Function: flexion, adduction, and medial rotation of the shoulder.

Latissimus Dorsi

Structure: lower back muscle. Function: extension, adduction, and medial rotation of the shoulder.

Upper Trapezius

Structure: upper section of the posterior shoulder

Function: Elevation and upward rotation

Middle Trapezius

Structure: Middle section of the posterior shoulder

Function: retraction

Lower Trapezius

Structure: Lower portion of posterior shoulder

Function: Depression and upward rotation

Supraspinatus

Structure: upper portion of shoulder girdle

Function: abduction and stabilization

Infraspinatus 

Structure: Below the supraspinatus; in the shoulder girdle

Function: lateral rotation and stabilization 

Subscapularis

Structure: anterior portion of shoulder girdle

Function: medial rotation and stabilization

Teres Minor

Structure: below infraspinatus in the shoulder girdle

Function: Lateral rotation and stabilization

Biceps Brachii (long head and short head)

Structure: anterior upper arm muscle

Function: S’ flexion + E’ flexion and supination 

Triceps Brachii

Structure: posterior upper arm muscle

Function: S’ Extension + E’ Extension

Flexor Carpi radialis

Structure: forearm muscle

Function: wrist flexion and radial deviation 

Flexor Carpi ulnaris

Structure: forearm muscles along ulna

Function: wrist flexion and ulnar deviation

Extensor Carpi radialis longus

Structure: forearm muscle

Function: wrist extension and radial deviation

Extensor carpi radialis brevis

Structure: forearm muscle

Function: wrist extension and radial deviation 

Extensor carpi ulnaris

Structure: forearm muscle

Function: Wrist extension and ulnar deviation 

Extensor Digitorum

Structure: forearm muscle that stretches down to the fingers

Function: Wrist extension and finger extension