Muscles of upper limb

The muscles of upper limb are divided into:

shoulder

arm

forearm

hand

Muscles of shoulder

Deltoid

Supraspinatus

Infraspinatus

Teres minor

Teres major

Subscapularis

Deltoid

Origin:

lateral one-third of clavicle, acromion, and spine of scapula

Insertion: deltoid tuberosity of humerus

Action: abducts the arm; anterior part may flexes and medically rotates the arm and the posterior part extends and laterally rotates arm

Supraspinatus

Origin:

the supraspinous fossa of the scapula

Insertion: upper of the three facets on the greater tubercle of the humerus.

Action: stabilizes shoulder joint and abducts the arm

Infraspinatus

Origin:

the infraspinous fossa of the scapula

Insertion: middle facets on the greater tubercle of the humerus.

Action: stabilizes shoulder joint and laterally rotates the humerus.

Teres minor

Origin:

the upper two-thirds of lateral border of the scapular on the dorsal surface.

Insertion: the lowest facet on the greater tubercle of the humerus.

Action: laterally rotates and adducts the humerus.

Teres major

Origin:

the dorsal surface near the inferior angle of the scapular.

Insertion: the crest of lesser tubercle of humerus.

Action:acts with the latissimus dorsi in addicting, extending and medial rotating the humerus.

Subscapularis

Origin: subscapular fossa

Insertion: lesser tubercle of humerus

Action: medially rotates the humerus and stabilizes the shoulder joint.

Antererior group

Biceps brachii

Coracobrachialis

Brachialis

Biceps brachii

Origin:

long head, supraglenoid tubercle; short head, coracoid process

Insertion: radical tuberosity

Action: supinator of forearm, flexor of elbow joint, weak flexor of should joint

Coracobrachialis

Origin: coracoid process

Insertion: the middle part of the medial border of humerus.

Action: adducts and weakly flexes the arm at the shoulder joint.

Brachialis

Origin:

the distal half of the front of the humerus

Insertion:

coronoid process and tuberosity of the ulna.

Action: main flexor of elbow joint.

Posterior group

Triceps brachii

Origin:

long head, infraglenoid tubercle; lateral head, above groove for radical n., medial head, below groove for radical n.

Insertion: olecranon of ulna

Action: extends elbow joint), long head can extend and adduct shoulder joint

Muscles of forearm

Anterior group

Superficial layer

Brachioradialis

Pronator teres

Flexor carpi radialis

Palmaris longus

Flexor carpi ulnaris

Pronator teres

Origin:

medical epicondyle of humerus and deep fascia of forearm

Insertion: middle of lateral surface of radius

Action:

pronation of forearm

Second layer

－flexor digitorum superficials

Third layer

Flexor digitorum profundus

Flexor pollicis longus

Fourth layer

－ pronator quadratus

Action: flex radiocarpal joint and fingers, pronate forearm

Posterior group

Superficial layer

Extensor carpi radialis longus

Extensor carpi radialis brevis

Extensor digitorum

Extensor digiti minimi

Extensor carpi ulnaris

Deep layer

Supinator

Abductor pollicis longus

Extensor pollicis brevis

Extensor pollicis longus

Extensor indicis

Action: extend radiocapral joint and fingers, and supinate forearm

Supinator

Origin: lateral epicondyle of humerus and upper part of lateral border of ulna

Insertion: upper third of anterior surface of radius

Action: supination of forearm

Muscles of hand

Lateral group－thenar

Abductor pollicis brevis

Flexor pollicis brevis

Opponens pollicis

Adductor pollicis

Action: flex, abduct, adduct and oppose thumb

Medial group－hypothenar

Abductor digiti minimi

Flexor digiti minimi brevis

Opponens digiti minimi

Action: flex, abduct , and oppose little finger