Muscles Of The Arm

Front 1

Back 1

Triceps Brachii
Long Head Origin: inferior margin of glenoid cavity
Medial Head Origin: posterior humerus
Lateral Head Origin: distal radial groove on posterior humerus
Insertion: Olecranon process of ulna
Action: Powerful arm extension, antagonist of forearm flexors (biceps brachii and bracialis)

Front 2

Back 2

Anconeus
Origin: lateral epicondyle of humerus
Insertion: lateral aspect of olecranon process of ulna
Action: Abducts ulna during forearm pronation; extends pronation

Front 3

Back 3

Biceps Brachii
Short Head Origin: coracoid process
Long Head Origin: intertubercular sulcus and within capsule of shoulder joint
Insertion: Radial Tuberosity
Action: Flexion of elbow and supination of forearm

Front 4

Back 4

Brachioradialis
Origin: Lateral ridge at distal end of humerus
Insertion: Base of styloid process of radius
Action: Synergist in forearm flexion

Front 5

Back 5

Brachialis
Origin: Distal portion of anterior humerus
Insertion: Coronoid process of ulna
Action: A major flexor of forearm

Front 6

Back 6

Pronator Teres
Origin: Medial epicondyle of humerus and coronoid process of ulna
Insertion: midshaft of radius
Action: Pronates and flexes forearm, weak elbow flexor

Front 7

lateral

Back 7

Flexor Carpi Radialis
Origin: Medial epicondyle of humerus
Insertion: Base of metacarpal 2 and 3
Action: Powerful flexor of wrist; abducts hand

Front 8

medial

Back 8

Flexor Carpi Ulnaris
Origin: Medial epicondyle of humerus and olecranon process and posterior surface of ulna
Insertion: Base of metacarpal 5; pisiform and hamate bones
Action: Powerful flexor of wrist; adducts hand

Front 9

Back 9

Palmaris Longus
Origin: Medial epicondyle of humerus
Insertion: Palmar aponeurosis, skin and fascia of palm
Action: Flexes wrist and tenses skin/fascia of palm

Front 10

Back 10

Flexor Digitorum Superficialis
Origin: Medial epicondyle of humerus, coronoid process of ulna and shaft of radius
Insertion: Middle phalanges of fingers 2-5
Action: Flexes wrist and middle phalanges of fingers 2-5

Front 11

Back 11

Flexor Pollicis Longus
Origin: Anteromedial surface of radius, interosseous membrane
Insertion: Distal phalanx of thumb
Action: Flexes thumb

Front 12

Back 12

Flexor Digitorum Profundus
Origin: Anteromedial surface of ulna, interosseous membrane, and coronoid process
Insertion: Distal phalanges of fingers 2-5
Action: Sole muscle that flexes distal phalanges; assists in wrist flexion

Front 13

Back 13

Pronator Quadratus
Origin: Distal portion of anterior ulnar surface
Insertion: Anterior surface of radius, distal end
Action: Pronates forearm

Front 14

Back 14

Extensor Carpi Radialis Longus
Origin: Lateral supracondyle ridge of humerus
Insertion: Base of metacarpal 2
Action: Extend and abduct wrist

Front 15

Back 15

Extensor Carpi Radialis Brevis
Origin: Lateral epicondyle of humerus
Insertion: Base of 3rd metacarpal
Action: Extend and abduct wrist

Front 16

Back 16

Extensor Digitorum
Origin: Lateral epicondyle of humerus
Insertion: By four tendons into distal phalanges of fingers 2-5
Action: Prime mover of finger extension, extends wrist

Front 17

Back 17

Extensor Carpi Ulnaris
Origin: Lateral epicondyle of humerus; posterior border of ulna
Insertion: Base of metacarpal 5
Action: Extends and adducts wrist

Front 18

Back 18

Subscapularis
Origin: Subscapular fossa of scapula
Insertion: Lesser tuberosity of humerus
Action: Medially rotates arm and adducts it; helps to hold humeral head in glenoid cavity of scapula

Front 19

Back 19

Supraspinatus
Origin: Supraspinous fossa of scapula
Insertion: Superior facet on greater tuberosity of humerus
Action: Initiates and assists deltoid in abduction of arm and acts with other rotator cuff muscles

Front 20

Back 20

Teres Minor
Origin: Superior part of lateral border of scapula
Insertion: Inferior facet on greater tuberosity of humerus
Action: Laterally rotate arm; helps to hold humeral head in glenoid cavity of scapula

Front 21

Back 21

Infraspinatus
Origin: Infraspinous fossa of scapula
Insertion: Middle facet on greater tuberosity of humerus
Action: Laterally rotate arm; helps to hold humeral head in glenoid cavity of scapula

Front 22

major

Back 22

Rhomboid Major
Origin: spinous processes of T2 - T5 vertebrae
Insertion: Medial border of scapula from level of spine to inferior angle
Action: Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall

Front 23

minor

Back 23

Rhomboid Minor
Origin: nuchal ligament and spinous processes of C7 and T1 vertebrae
Insertion: Medial border of scapula from level of spine to inferior angle
Action: Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall

Front 24

longus

Back 24

Extensor Pollicis Longus
Origin: Posterior surface of middle 1/3 of ulna and interosseous membrane
Insertion: Base of distal phalanx of thumb
Action: Extends distal phalanx of thumb at carpometacarpal and interphalangeal joints

Front 25

brevis

Back 25

Extensor Pollicis Brevis
Origin: Posterior surfaces of radius and interosseous membrane
Insertion: Base of proximal phalanx of thumb
Action: Extends proximal phalanx of thumb at carpometacarpal joint

Front 26

Back 26

Abductor Pollicis Longus
Origin: Posterior surfaces of ulna, radius and interosseous membrane
Insertion: Base of 1st metacarpal
Action: Abducts thumb and extends it at carpometacarpal joint

Front 27

Back 27

Abductor Pollicis Brevis
Origin: Flexor retinaculum and tubercles of scaphoid and trapezium
Insertion: Lateral side of base of proximal phalanx of thumb
Action: Abducts thumb and helps oppose it

Front 28

Back 28

Deltoid
Origin: Lateral third of clavicle, acromion, and spine of scapula
Insertion: Deltoid tuberosity of humerus
Action:
Anterior part: flexes and medially rotates arm
Middle part: abducts arm
Posterior part: extends and laterally rotates arm

Front 29

Back 29

Coracobrachialis
Origin: Tip of coracoid process of scapula
Insertion: Middle third of medial surface of humerus
Action: Helps to flex and adduct arm