Upper Extremity Muscles

Front 1

Trapezius (superior fibers)

Back 1

O: External occipital protuberance, the medial portion of superior nuchal line of occiput, medial margin of ligamentum nuchae

I: Posterior border of lateral 1/3 of the clavicle

A: Unilaterally: Elevation and upper rotation of the scapula; ipsilateral side bending (laterally flex) and contralateral rotation of the head;
Bilaterally: extend the head and neck

N: Accessory nerve (CN XI) and branches of C3, C4

Front 2

Trapezius (middle fibers)

Back 2

O: Inferior aspect of ligamentum nuchae, spinous proces of 7th cervical and upper thoracic

I: Medial margin of acromion process of scapula, superior lip of posterior border of spine of
scapula

A: Retraction of scapula, adduct scapula, stabilize scapula

N: CN XI and C3, C4

Front 3

Trapezius (inferior fibers)

Back 3

O: Spinous process of inferior thoracic vertebrae

I: Medial end of the spine of scapula

A: Depression of the scapula, upwardly rotate the scapula

N: CN XI and C3, C4

Front 4

Rhomboid Major

Back 4

O: Spinous processes of T2 - T5 vertebrae

I: Posterior surface of medial border of scapula from the root of the spine of the scapula to the
inferior angle

A: Elevates and retracts the scapula, adduct the scapula, downwardly rotate the scapula

N: Dorsal scapular nerve (C4-C5)

Front 5

Rhomboid Minor

Back 5

O: Lower end of ligamentum nuchae and spinous process of C7 and T1 vertebrae

I: Posterior surface of medial border of scapula at the root of the spine of the scapula

A: Elevates and retracts the scapula, adduct the scapula, downwardly rotate the scapula

N: Dorsal scapular nerve (C4-C5)

Front 6

Levator Scapulae

Back 6

O: Transverse processes of C1-C4 vertebrae at the posterior tubercles

I: Posterior surface of medial border of scapula from superior angle to root of spine of the scapula

A: Unilaterally: Elevates scapula; ipsilateral side bending and rotation of the head, downwardly rotate the scapula
Bilaterally: extend the head and neck

N: Anterior rami of C3 and C4 spinal nerves and by branches (C5) from the dorsal scapular nerve

Front 7

Latissimus Dorsi

Back 7

O: Spinous processes of T7-T12 and related interpinous ligaments; via the thoracolumbar fascia to
the spinous process of the lumbar vertebrae, related interspinous ligaments, and posterior iliac crest; last three or four ribs, inferior angle of the scapula

I: Floor of the intertubercular sulcus

A: Adduction, medial rotation, and extension of the arm at glenohumeral joint,

N: Thoracodorsal nerve (C6,C7,C8)

Front 8

Teres Major

Back 8

O: Lower one third of lateral border of the scapula

I: Medial lip of intertubercular sulcus on the anterior surface of the humerus; crest of the lesser tubercle of the humerus

A: Medial rotation, extension of the arm, and adduction at the glenohumeral joint

N: lower subscapular nerve (C5, C6)

Front 9

Deltoid (posterior fibers)

Back 9

O: Inferior edge of the crest of the spine of the scapula

I: Deltoid tuberosity of the humerus

A: Abduct, extension, horizontal abduction, external rotation - humerus

N: Axillary (C5, C6)

Front 10

Deltoid (middle fibers)

Back 10

O: Lateral margin of the acromion

I: Deltoid tuberosity of the humerus

A: Abduction of humerus

N: Axillary (C5, C6)

Front 11

Deltoid (anterior fibers)

Back 11

O: Anterior border of the lateral 1/3 of clavicle

I: Deltoid tuberosity of the humerus

A: Abduct, flexion, horizontal adduction, internal rotation of the humerus

N: Axillary (C5, C6)

Front 12

Pectoralis major

Back 12

O: Clavicular head - anterior surface of medial half of clavicle;
Sternocostal head - anterior surface of the sternum; first seven costal cartilages; sternal end of the sixth rib; aponeurosis of external oblique

I: Lateral lip of the intertubercular sulcus of humerus; crest of greater tubercle of humerus

A: All fibers: flexion, adduction of glenohumeral (GH) joint, and medial rotation of glenohmeral joint; assist to elevate the thorax during forced inhalation with arm fixed;
Clavicular head: flexion of the extended shoulder horizontal adduction of GH joint;
Sternocostal head: extension of the flexed shoulder

N: Medial and lateral pectoral nerves (C5-T1)
Clavicular head: lateral pectoral (C5, C6)
Sternocostal head: lateral and medial pectoral nerves (C7, C8, T1)

Front 13

Pectoralis minor

Back 13

O: Anterior surface of the superior borders of third to fifth ribs; and from deep fascia overlying the
related intercostal spaces

I: Coracoid process of scapula (medial border and upper surface)

A: Stabilization of the scapula against thoracic wall by pulling the coracoid process anteriorly,
downward rotation of the scapula; depression of the scapula, abduction of the scapula,

N: Medial pectoral nerve (C8, T1) (some with fibers from the communicating branch of the lateral pectoral nerve C6, C7,C8,T1)

Front 14

Subclavius

Back 14

O: First rib at junction between rib and costal cartilage

I: Groove on inferior surface of middle one-third of clavicle

A: Anchors and stabilizes the sternoclavicular joint; depresses the clavicle, draws clavicle anteriorly, elevates first rib (assisting with inhalation)

N: nerve to subclavius (i.e. subclavian nerve) (C5,C6)

Front 15

Serratus anterior

Back 15

O: Lateral (i.e. external) surfaces of upper 8-9 ribs and deep fascia overlying the related intercostal spaces

I: Costal (i.e. anterior) surface of medial border of scapula

A: With the origin fixed: abduct/protraction of the scapula, upwardly rotate the scapula, depresses the scapula, holds the medial and inferior borders of the scapula against the rib cage.
With the scapula fixed: may act to elevate the thorax during forced inhalation

N: long thoracic nerve (C5, C6, C7)

Front 16

Coracobrachialis

Back 16

O: Apex of coracoid process

I: Linear roughening on medial midshaft of humerus;

A: Flexor of the arm at the glenohumeral joint; adducts the shoulder at the GH joint

N: Musculocutaneous nerve (C5, C6, C7)

Front 17

Supraspinatus

Back 17

O: Medial two-third of the supraspinous fossa of scapula and deep fascia that covers the muscle

I: Most superior facet on the greater tubercle of the humerus

A: Rotator cuff muscle, assists with maintaining glenohumeral head stability; abduction of shoulder at the glenohumeral joint

N: Suprascapular nerve (C4, C5, C6)

Front 18

Infraspinatus

Back 18

O: Medial two-third of the infraspinous fossa of scapula and deep fascia that covers the muscle

I: Middle facet on posterior surface of the greater tubercle of the humerus

A: Rotator cuff muscle, assists with maintaining glenohumeral head stability; lateral rotation of the arm at glenohumeral joint, adduction of the shoulder at GH joint

N: Suprascapular nerve (C5, C6)

Front 19

Teres Minor

Back 19

O: Upper two-thirds of lateral border of scapula

I: Inferior facet on the posterior surface of the greater tubercle of the humerus

A: Rotator cuff muscle, assists with maintaining glenohumeral head stability; lateral rotation of the
arm at the glenohumeral joint, adduction of the shoulder at the GH joint

N: Axillary nerve (C5, C6)

Front 20

Subscapularis

Back 20

O: Medial two-thirds of subscapular fossa

I: Lesser tubercle of the humerus

A: Rotator cuff muscle, assist with maintaining glenohumeral head stability; medial rotation of the
shoulder at the glenohumeral joint

N: Upper and lower subscapular nerves (C5, C6,C7)

Front 21

Biceps brachii

Back 21

O: Long head-supraglenoid tubercle of the scapula
Short head-apex of coracoid process of the scapula

I: Radial tuberosity and fascia of the forearm via bicipital apponeurosis

A: Flexion of the forearm at the elbow joint and supinator of the forearm; accessory flexor of the
arm at the glenohumeral joint

N: Musculocutaneous nerve (C5, C6)

Front 22

Brachialis

Back 22

O: Distal half of anterior aspect of the humerus (medial and lateral surfaces) and adjacent intermuscular septae

I: Coronoid process and tuberosity of ulna

A: Flexion of the forearm at elbow in all positions

N: Musculocutaneous (C5, C6)

Front 23

Triceps brachii

Back 23

O: Long head - infraglenoid tubercle of scapula
Medial head - posterior surface of the distal half of humerus (distal to radial groove)
Lateral head - posterior surface of the proximal half of humerus (superior to radial groove)

I: Olecranon

A: All heads: extension of the forearm at elbow joint. Long head: can also extend and adduct the shoulder at the GH joint,

N: radial nerve (C6, C7, C8)

Front 24

Anconeus

Back 24

O: Lateral epicondyle of humerus

I: Olecranon process and proximal posterior surface of ulna

A: Accessory extension of the elbow joint; stabilize elbow joint; abducts ulna in pronation

N: Radial nerve (C6, C7, C8) (via branch to medial head of the triceps brachii)

Front 25

Pronator Teres

Back 25

O: Humeral head - medial epicondyle (i.e. site of common flexor tendon origin) and adjacent supraepicondylar ridge
Ulnar head - medial side of coronoid process

I: Roughening on lateral surface, midshaft, of the radius

A: pronation of the forearm (at the radio-ulnar joints)

N: median nerve (C6, C7)

Front 26

Flexor carpi radialis

Back 26

O: Medial epicondyle of humerus (i.e. site of common flexor tendon origin) from medial epicondyle of humerus

I: Base of 2nd and 3rd metacarpals

A: Flexion and abduction of the wrist; weak elbow flexion

N: Median (C6, C7)

Front 27

Flexor carpi ulnaris

Back 27

O: Humeral head - medial epicondyle of humerus (i.e. site of common flexor tendon origin) Ulnar head - olecranon and posterior proximal 2/3 of ulna

I: Pisiform bone, and then via pisohamate and pisometacarpal ligaments into the hook of hamate and base of 5th metacarpal bone

A: Flexion and adduction of the wrist joint; weak elbow flexion

N: Ulnar nerve (C7,C8)

Front 28

Palmaris Longus

Back 28

O: Medial epicondyle of humerus (i.e. site of common flexor tendon origin)

I: Palmar aponeurosis of hand; flexor retinaculum

A: flexion of wrist; resists shearing forces when gripping; weak flexion of the elbow

N: median nerve (C7, C8)

Front 29

Flexor digitorum superficialis

Back 29

O: Humero-ulnar head: medial epicondyle of humerus, adjacent margin of coronoid process, and interosseous membrane
Radial head: oblique line of radius

I: Four tendons, which attach to the palmar surfaces of the middle phalanges of the index, middle, ring, and little fingers

A: Flexion of proximal interphalangeal joints of digits 2-5; can also flex metacarpophalangeal joints of the same fingers and the wrist joint

N: Median nerve (C7, C8, T1)

Front 30

Flexor digitorum profundus

Back 30

O: Anterior and medial surfaces of the proximal ¾ of ulna and anterior medial half of interosseous membrane

I: Four tendons, which attach to the palmar surfaces of the distal phalanges of digits 2-5

A: Flexion of distal interphalangeal joints of the of digits 2-5; can also flex metacarpophalangeal joints of the same fingers and the wrist joint

N: Lateral half: anterior interosseous (median) C8,T1
Medial half: ulnar C8,T1

Front 31

Flexor pollicis longus

Back 31

O: Anterior surface of radius and radial half of interosseous membrane

I: Palmar surface of base of distal phalanx of thumb

A: Flexion of interphalangeal joint of the thumb; can also flex metacarpophalangeal and carpometacarpal joint of the thumb; assist to flex the wrist (weak)

N: Anterior interosseous nerve (median) (C8,T1)

Front 32

Pronator quadratus

Back 32

O: Linear ridge on distal anterior, medial surface of ulna

I: Distal anterior, lateral surface of radius

A: Pronation of the forearm

N: Anterior interosseous nerve (median) (C8, T1)

Front 33

Brachioradialis

Back 33

O: Proximal 2/3 of lateral supracondylar ridge of humerus and adjacent intermuscular septum

I: Styloid process of radius

A: Accessory flexion of elbow (humero-ulnar) joint when forearm is midpronated; assist with pronation and supination of the forearm with resistance (weak)

N: radial nerve (C5, C6, C7) before division into superficial and deep branches

Front 34

Extensor carpi radialis longus

Back 34

O: distal 1/3 part of lateral supracondylar ridge of humerus and adjacent intermuscular septum

I: Dorsal surface of base of 2nd metacarpal

A: Extension and abduction of the wrist; assists with elbow flexion (weak)

N: Rradial nerve (C6, C7) before division into superficial and deep branches

Front 35

Extensor carpi radialis brevis

Back 35

O: Lateral epicondyle of humerus and adjacent intermuscualr septum; part of common extensor tendon

I: Dorsal surface of base of 3rd metacarpal

A: Extension and abduction of the wrist; assists to flex the elbow (weak)

N: Deep branch of radial nerve (C7, C8) before penetrating supinator muscle

Front 36

Extensor carpi ulnaris

Back 36

O: Lateral epicondyle of humerus and posterior border of ulna; part of common extensor tendon from lateral epicondyle

I: Tubercle on the base of the medial side of the 5th metatcarpal

A: Extension and adduction of the wrist

N: Posterior interosseous nerve (radial nerve) (C7, C8)

Front 37

Extensor digitorum

Back 37

O: lateral epicondyle of humerus and adjunct intermuscular septum and deep fascia; part of common extensor tendon from the lateral epicondyle of humerus

I: Four tendons, which insert via extensor hood into the dorsal aspect of the bases of the middle and distal phalanges of digits 2-5

A: Extension of the index, middle, ring, and little finger (i.e. digits 2-5) MCPs and IPs; can also extend the wrists

N: Posterior interosseous nerve (radial) (C7, C8)

Front 38

Extensor indicis proprius

Back 38

O: Posterior surface of distal shaft of ulna (distal to extensor pollicis longus) and adjacent interosseous Membrane

I: Extensor hood of index finger

A: Extension of index (2nd) finger, may assist to extend the wrist (RC joint, weak)

N: Posterior interosseous nerve (radial) (C7, C8)

Front 39

Extensor digiti minimi

Back 39

O: Lateral epicondyle of humerus and adjunct intermuscular septum together with extensor
digitorum

I: Extensor hood of the little finger

A: Extension of the little finger

N: Posterior interosseous nerve (radial) (C7, C8)

Front 40

Supinator

Back 40

O: Superficial part - lateral epicondyle of humerus, radial collateral and annular ligaments
Deep part – supinator crest of the ulna

I: Anterior and lateral surface of proximal one-third of radius superior to the anterior oblique line

A: Supination (of the radio-ulnar joints)

N: Deep branch of the radial nerve (C6, C7) (radial) before becoming the posterior interosseous n.

Front 41

Abductor pollicis longus

Back 41

O: Posterior surfaces of ulna and radius (distal to the attachments of supinator and anconeus), and
intervening interosseous membrane

I: Lateral side of base of 1st metacarpal

A: Abduction of the carpometacarpal joint of the thumb; accessory extension of the thumb; abduct the wrist (radiocarpal joint; weak)

N: Posterior interosseous nerve (radial) (C7, C8,)

Front 42

Extensor pollicis longus

Back 42

O: Posterior surfaces of ulna (distal to abductor pollicis longus), and the adjacent interosseous membrane

I: Dorsal surface of base of distal phalanx of thumb

A: Extension of the interphalangeal joint of the thumb; can also extend carpometacarpal and
metacarpophalangeal joints of the thumb; abduction of the wrist (radiocarpal joint; weak)

N: Posterior interosseous nerve (radial) (C7, C8)

Front 43

Extensor pollicis brevis

Back 43

O: Posterior surfaces of radius (distal to abductor pollicis longus), and the adjacent interosseous
membrane

I: Dorsal surface of base of proximal phalanx of thumb

A: Extension of the metacarpophalangeal joint of the thumb; can also extend the carpometacarpal
joint of the thumb; abduction of the wrist (radiocarpal joint)

N: Posterior interosseous nerve (radial) (C7, C8)

Front 44

Abductor pollicis brevis

Back 44

O: Tubercles of scaphoid and trapezium and adjacent flexor retinaculum

I: Base of proximal phalanx and extensor hood of the thumb

A: Abduction of the thumb at the metacarpophalangeal and carpometacarpal joints

N: Recurrent branch of median nerve (C8, T1)

Front 45

Flexor pollicis brevis

Back 45

O: Superficial head: Flexor retinaculum
Deep head: Trapezium tubercle, trapezoid, and capitate

I: Base of proximal phalanx of the thumb

A: Flexion of the thumb at the metacarpophalangeal and carpometacarpal joints; assists in opposition of thumb

N: Superficial head: Recurrent branch of median nerve (C8, T1)
Deep head: Ulnar C8,T1

Front 46

Opponens pollicis

Back 46

O: Tubercle of the trapezium and flexor retinaculum

I: Entire length of the 1st metacarpal on the radial surface

A: Opposition of thumb at carpometacarpal joint (bringing pads of the thumb and fifth finger together)

N: Recurrent branch of median nerve (C8, T1)

Front 47

Abductor digiti minimi

Back 47

O: Pisiform, the pisohamate ligament, and tendon of flexor carpi ulnaris

I: Base of proximal phalanx of little finger, ulnar surface

A: Abduction of the little finger at the metacarpophalangeal joint

N: Deep branch of ulnar nerve (C8, T1)

Front 48

Flexor digiti minimi brevis

Back 48

O: Hook of hamate and flexor retinaculum

I: Base of proximal phalanx of little finger palmar surface

A: Flexion of the little finger at the metacarpophalangeal joint; assist in opposition of the 5th finger toward the thumb

N: Deep branch of ulnar nerve (C8, T1)

Front 49

Opponens digiti minimi

Back 49

O: Hook of hamate and flexor retinaculum

I: Shaft of the 5th metacarpal, ulnar surface

A: Opposition of the 5th finger at the carpometacarpal joint

N: Deep branch of ulnar nerve (C8, T1)

Front 50

Adductor pollicis

Back 50

O: Transverse head – 3rd metacarpal bone
Oblique head – capitate and base of 2nd and 3rd metacarpals

I: Base of proximal phalanx and hood of the thumb

A: Adducts thumb (carpometacarpal and metacarpophalangeal joints)

N: Deep branch of ulnar nerve (C8, T1)

Front 51

Dorsal interrossei

Back 51

O: Adjacent sides of all metacarpal

I: Extensor hood (aponeurosis) and bases of proximal phalanges of index, middle and ring fingers

A: Abduction of index, middle, and ring fingers at the metacarpophalangeal joints; flex digits at 2nd, 3rd, 4th fingers at metacarpophalangeal joint and extend 2nd, 3rd, 4th fingers at interphalangeal joints

N: Deep branch of ulnar nerve (C8, T1)

Front 52

Volar (Palmar) interossei

Back 52

O: Sides of metacarpals 2, 4 and 5

I: Extensor hood of the thumb, index, ring and little fingers and proximal phalanx of the thumb

A: Adduction of the index, ring, and little fingers toward the 3rd finger at the metacarpophalangeal joints; assists to flex (thumb, 2nd, 4th, 5th, ) digits at metacarpophalangeal joint and assist to extend thumb, 2nd, 4th, and 5th fingers at interphalangeal joints

N: Deep branch of ulnar nerve (C8, T1)

Front 53

Lumbricals

Back 53

O: 1st and 2nd – lateral two tendons of flexor digitorum profundus
3rd and 4th - medial three tendons of flexor digitorum profundus

I: Extensor hoods of index, ring, middle, and little fingers

A: Flexion of the (2nd to 5th fingers) metacarpophalangeal joints and extension of the (2nd to 5th fingers) at the interphalangeal joints

N: Medial two by the deep branch of the ulnar nerve (C8, T1)
Lateral two by the digital branches of the median nerve (C8, T1)/