Posterior Forearm Muscles

Question 0

Insertion of brachioradialis

Answer 0

Lateral surface of distal end of radius proximal to styloid process

Question 1

Origin of brachioradialis

Answer 1

Proximal two thirds of lateral supra-epicondylar ridge of humerus

Question 2

Innervation of brachioradialis

Answer 2

Radial nerve (C5, C6, C7)

Question 3

Action of brachioradialis

Answer 3

Relatively weak flexion of elbow joint, maximal when forearm is in midpronated position

Question 4

Origin of extensor carpi radialis longus

Answer 4

Lateral supra-epicondylar ridge of humerus

Question 5

Insertion of extensor carpi radialis longus

Answer 5

Dorsal aspect of base of 2nd metacarpal

Question 6

Innervation of extensor carpi radialis longus

Answer 6

Radial nerve (C6, C7)

Question 7

Action of extensor carpi radialis longus

Answer 7

Extend and abduct wrist joint

Question 8

Origin of extensor carpi radialis brevis

Answer 8

Lateral epicondyle of humerus

Question 9

Insertion of extensor carpi radialis brevis

Answer 9

Dorsal aspect of base of 3rd metacarpal

Question 10

Innervation of extensor carpi radialis brevis

Answer 10

Deep branch of radial nerve (C7, C8)

Question 11

Action of extensor carpi radialis brevis

Answer 11

Extend and abduct wrist joint

Active during first clenching

Question 12

Origin of extensor digitorum

Answer 12

Lateral epicondyle of humerus

Question 13

Insertion of extensor digitorum

Answer 13

Extensor expansions of medial four fingers

Question 14

Innervation of extensor digitorum

Answer 14

Deep branch of radial nerve (C7, C8)

Question 15

Action of extensor digitorum

Answer 15

Extend wrist joint
Extend medial four fingers primarily at metacarpophalangeal joints
Secondarily at interphalangeal joints

Question 16

Origin of extensor digiti minimi

Answer 16

Lateral epicondyle of humerus

Question 17

Insertion of extensor digiti minimi

Answer 17

Extensor expansion of 5th finger

Question 18

Innervation of extensor digiti minimi

Answer 18

Posterior interosseous nerve (C7, C8)

Question 19

Action of extensor digiti minimi

Answer 19

Extends wrist joint
Extends 5th finger primarily at metacarpophalangeal joint
Secondarily at interphalangeal joint

Question 20

Origin of extensor carpi ulnaris

Answer 20

Lateral epicondyle of humerus

Posterior border of ulna via a shared aponeurosis

Question 21

Insertion of extensor carpi ulnaris

Answer 21

Dorsal aspect of base of 5th metacarpal

Question 22

Innervation of extensor carpi ulnaris

Answer 22

Posterior interosseous nerve (C7, C8)

Question 23

Action of extensor carpi ulnaris

Answer 23

Extends and adducts wrist joint

Also active during fist clenching

Question 24

Origin of supinator

Answer 24

Lateral epicondyle of humerus Radial collateral and anular ligaments Supinator fossa Crest of ulna

Question 25

Insertion of supinator

Answer 25

Lateral, posterior, and anterior surfaces of proximal third of radius

Question 26

Innervation of supinator

Answer 26

Deep branch of radial nerve (C7, C8)

Question 27

Action of supinator

Answer 27

Supinates forearm | Rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)

Question 28

Origin of abductor pollicis longus

Answer 28

Posterior surface of proximal halves of ulna, radius, and interosseous membrane

Question 29

Insertion of abductor pollicis longus

Answer 29

Base of 1st metacarpal

Question 30

Innervation of abductor pollicis longus

Answer 30

Posterior interosseous nerve (C7, C8) | Continuation of deep branch of radial nerve

Question 31

Action of abductor pollicis longus

Answer 31

Extends wrist joint | Abducts thumb and extends it at carpometacarpal joint

Question 32

Origin of extensor pollicis longus

Answer 32

Posterior surface of middle third of ulna and interosseous membrane

Question 33

Insertion of extensor pollicis longus

Answer 33

Dorsal aspect of base of distal phalanx of thumb

Question 34

Innervation of extensor pollicis longus

Answer 34

Posterior interosseous nerve (C7, C8) | Continuation of deep branch of radial nerve

Question 35

Action of extensor pollicis longus

Answer 35

Extends wrist joint Extends distal phalanx of thumb at interphalangeal joint Extends metacarpophalangeal joint Extends carpometacarpal joint

Question 36

Origin of extensor pollicis brevis

Answer 36

Posterior surface of distal third of radius and interosseous membrane

Question 37

Insertion of extensor pollicis brevis

Answer 37

Dorsal aspect of base of proximal phalanx of thumb

Question 38

Innervation of extensor pollicis brevis

Answer 38

Posterior interosseous nerve (C7, C8) | Continuation of deep branch of radial nerve

Question 39

Action of extensor pollicis brevis

Answer 39

Extends wrist joint Extends proximal phalanx of thumb at metacarpophalangeal joint Extends carpometacarpal joint

Question 40

Origin of extensor indicis

Answer 40

Posterior surface of distal third of ulna and interosseous membrane

Question 41

Insertion of extensor indicis

Answer 41

Extensor expansion of 2nd finger

Question 42

Innervation of extensor indicis

Answer 42

Posterior interosseous nerve (C7, C8) | Continuation of deep branch of radial nerve

Question 43

Action of extensor indicis

Answer 43

Extends wrist joint Extends 2nd finger (enabling its independent extension) Helps extend hand at wrist