Upper limb muscle actions and innervations

Question 1

Pec Major

Answer 1

adducts, medially rotates humerus; clavicular head flexes humerus

medial and lateral pectoral nerves

Question 2

Pec minor

Answer 2

protracts and depresses the scapula, also accessory muscle of respiration

medial pectoral nerve

Question 3

Subclavius

Answer 3

pulls lateral end of clavicle downward and forward, thereby acting to resist excessive shoulder elevation and protraction

Nerve to subclavius

Question 4

BTW, what goes through the clavipectoral fascia?

Answer 4

cephalic vein, thoracoacromial artery, lateral pectoral nerve

Question 5

Deltoid

Answer 5

flex and medially rotate humerus
extend and laterally rotate humerus
abduct humerus

axillary n

Question 6

Supraspinatus

Answer 6

initiate abduction

suprascapular n

Question 7

Infraspinatus

Answer 7

lateral rotation of humerus

suprascapular n

Question 8

teres minor

Answer 8

lateral rotation of humerus

axillary n

Question 9

Teres Major

Answer 9

extend, adduct, medially rotate humerus (mini deltoid)

lower subscapular n

Question 10

Subscaplaris

Answer 10

multipennate. medial rotation of humerus

Upper and lower subscapular n.

Question 11

serratus anterior

Answer 11

protract scaupla, upwardly rotate glenoid cavity, fixate scapula to thoracic wall

long thoracic n.

Question 12

Biceps Brachii

Answer 12

flex forarm and supinate the hand; most powerful supinator of hand above 90 of flexion; long head also assists in flexion of the arm.

musculocutaneous n.

long head attaches to supraglenoid tubercle of scapula
short head to coracoid process of scapula

i: radial tuberosity

Question 13

Brachialis

Answer 13

flexion of forearm (most powerful of three primary forearm flexors)

musculocutaneous n.

Question 14

Brachioradialis

Answer 14

flexion of the forearm (best mechanical advantage when hand is midway between supination and pronation, i.e. handshake)

radial n.

Question 15

Coracobrachialis

Answer 15

flexion, adduction of humerus

musculocutaneous n.

Question 16

Triceps brachii

Answer 16

O: long head; infraglenoid tubercle of scapula
lateral head- posterior surface of humerus proximal to radial groove
medial head- posterior surface of humerus distal to radial groove

a: extend the forearm; long head also acts at the shoulder joint to extend and adduct the arm

Radial n.

Question 17

Anconeus

Answer 17

O; posterior surface lateral epicondyle of humerus
i: lateral surface of olecranon and proximal posterior surface of ulna

assists triceps in extension of the forearm

radial n.

Question 18

Pronator teres

Answer 18

pronates and slightly flexes forearm

median n.

Question 19

flexor carpi radialis

Answer 19

flexes wrist and abducts hand

median n

Question 20

palmarus longus

Answer 20

flexes the wrist

median n.

Question 21

flexor carpi ulnaris

Answer 21

flexes wrist, adducts hand

*** ulnar n.

Question 22

Flexor digitorum superficialis

Answer 22

flexes proximal I-P joints, assists in flexion of the M-P joints, wrist and forearm

median n.

Question 23

flexor digitorum profundus

Answer 23

flexion of distal I-P joints, assists in flexion of proximal IP, MP and wrist joints

N: lateral portion- median n.
medial portion (to digits 4  & 5) Ulnar n.

Question 24

Plexor pollicis longus

Answer 24

flicks your bic: flexes thumb

median n. (anterior interosseous branch)

Question 25

Pronator quadratus

Answer 25

pronates the hand

median n. (anterior interosseous branch)

Question 26

Muscles of anterior forearm by layer

Answer 26

Superficial layer: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris

Intermediate layer: flexor digitorum superficialis

deep layer: flexor digitorum profundus, flexor pollicis longus

Distal layer: pronator quadratus

Question 27

Extensor carpi radialis longus

Answer 27

extends and abducts the hand

radial n.

Question 28

extensor carpi radialis brevis

Answer 28

extends and assists in abduction of the hand

radial n.

Question 29

Extensor digitorum

Answer 29

extends the digits and assists in extension of the hand

radial n.

Question 30

extensor digiti minimi

Answer 30

extension of fifth digit

radial n.

Question 31

extensor carpi ulnaris

Answer 31

extends and adducts the hand

radial n.

Question 32

Abductor pollicis longus

Answer 32

abduccs the thumb and wrist, assists with extension of the thumb

radial n.

Question 33

extensor pollicis brevis

Answer 33

extends proximal phalanx of thumb and first metacarpal

radial n.

Question 34

extensor pollicis longus

Answer 34

extends the thumb (I-P and M-P joints)

radial n.

Question 35

Extensor indicis

Answer 35

extends the index finger

radial n.

Question 36

supinator

Answer 36

supinates the hand

radial n.

Question 37

Abductor pollicis brevis

Answer 37

abducts thumb

median n. (recurrent)

Question 38

Flexor pollicis brevis

Answer 38

flexion of the thumb at carpometacarpal and metacarpophalangeal joint

superficial head: median n. (recurrent);
deep head: deep branch ulnar n.

Question 39

Opponens pollicis

Answer 39

opposition of thumb to digits

median n. (recurrent)

Question 40

Abductor digiti minimi

Answer 40

abducts and flexes metacarpophalangeal joint of digiti minimi

ulnar n. (deep branch)

Question 41

flexor digiti minimi

Answer 41

flees digiti minimi at metacarpophalangeal joint

ulnar n (deep branch)

Question 42

Opponens digiti minimi

Answer 42

pulls fifth metacarpal towards thumb during opposition or when grasping

ulnar n. (deep branch)

Question 43

lumbricals

Answer 43

flexes MCP joints and extends I-P joints

median (1 & 2), ulnar (3 & 4)

Question 44

Adductor pollicis

Answer 44

adducts thumb (oblique and transverse heads)

ulnar (deep branch)

Question 45

palmar interossei

Answer 45

adducts digits 1-, flexes M-P joints and extends I-P joints of 1-5

ulnar (deep branch)

Question 46

dorsal interossei

Answer 46

abduct digits 2-4, flex M-P joints and extend I-P joints of digits 2-4

Ulnar (deep branch)