Posterior Compartment Of Forearm Muscles

Question 0

What muscles make up the deep layer of the posterior compartment of the forearm?

Answer 0

Supinator is the only one not considered and “outcropping” muscle. The other deep muscles include, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and extensor indicis

Question 1

What muscles make up the superficial layer of the posterior compartment of the forearm?

Answer 1

Brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris

Question 2

Origin of brachioradialis

Answer 2

Proximal two thirds of lateral supraepicondylar ridge of humerus

Question 3

Insertion of brachioradialis

Answer 3

Lateral surface of distal end of radius proximal to styloid process

Question 4

Innervation of brachioradialis

Answer 4

Radial nerve (c5,c6,c7)

Question 5

Action of brachioradialis

Answer 5

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

Question 6

Origin of extensor carpi radialis longus

Answer 6

Lateral supra-epicondylar ridge of humerus

Question 7

Insertion of the extensor carpi radialis longus

Answer 7

Dorsal aspect of base of 2nd metacarpal

Question 8

Innervation of extensor carpi radialis longus

Answer 8

Radial nerve (c6 and c7)

Question 9

Actions of extensor carpi radialis longus

Answer 9

Extend and abduct wrist joint

Question 10

Origin of extensor carpi radialis brevis

Answer 10

Lateral epicondyle of humerus

Question 11

Insertion of extensor carpi radialis brevis

Answer 11

Dorsal aspect of base of 3rd metacarpal

Question 12

Innervation of extensor carpi radialis brevis

Answer 12

Deep branch of radial nerve (c7 and c8)

Question 13

Actions of extensor carpi radialis brevis

Answer 13

Extend and abduct wrist joint, active during fist clenching

Question 14

Origin of extensor digitorum

Answer 14

Lateral epicondyle of humerus

Question 15

Insertion of extensor digitorum

Answer 15

Extensor expansions of medial four fingers

Question 16

Innervation of extensor digitorum

Answer 16

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 17

Actions of extensor digitorum

Answer 17

Extend wrist joint, extend medial four fingers primarily at metacarpophalangeal joints, secondarily at interphalangeal joint

Question 18

Origin of extensor digiti minimi

Answer 18

Lateral epicondyle of humerus

Question 19

Insertion of extensor digiti minimi

Answer 19

Extensor expansion of 5th finger

Question 20

Innervation of extensor digiti minimi

Answer 20

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 21

Actions of extensor digiti minimi

Answer 21

Extends wrist joint, extends 5th finger primarily at metacarpophalangeal joint, secondarily at interphalangeal joint

Question 22

Origin of extensor carpi ulnaris

Answer 22

Lateral epicondyle of humerus, and posterior border of ulna via a shared aponeurosis

Question 23

Insertion of extensor carpi ulnaris

Answer 23

Dorsal aspect of base of 5th metacarpal

Question 24

Innervation of extensor carpi ulnaris

Answer 24

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 25

Actions of extensor carpi ulnaris

Answer 25

Extends and adducts wrist joint (also active during fist clenching)

Question 26

Origin of supinator

Answer 26

Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator fossa, crest of ulna

Question 27

Insertion of supinator

Answer 27

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

Question 28

Innervation of supinator

Answer 28

Deep branch of radial nerve (c7 and c8)

Question 29

Actions of supinator

Answer 29

Supinates forearm, rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)

Question 30

Origin of abductor pollicis longus

Answer 30

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

Question 31

Insertion of abductor pollicis longus

Answer 31

Base of 1st metacarpal

Question 32

Innervation of abductor pollicis longus

Answer 32

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 33

Actions of abductor pollicis longus

Answer 33

Extends wrist joint; abducts thumb and extends it at carpometacarpal joint

Question 34

Origin of extensor pollicis longus

Answer 34

Posterior surface of middle third of ulna and interosseous membrane

Question 35

Insertion of extensor pollicis longus

Answer 35

Dorsal aspect of base of distal phalanx of thumb

Question 36

Innervation of extensor pollicis longus

Answer 36

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 37

Actions of extensor pollicis longus

Answer 37

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

Question 38

Origin of extensor pollicis brevis

Answer 38

Posterior surface of distal third of radius and interosseous membrane

Question 39

Insertion of extensor pollicis brevis

Answer 39

Dorsal aspect of base of proximal phalanx of thumb

Question 40

Innervation of extensor pollicis brevis

Answer 40

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 41

Actions of extensor pollicis brevis

Answer 41

Extends wrist joint

Extends proximal phalanx of thumb at metacarpophalangeal joint, extends carpometacarpo joint

Question 42

Origin of extensor indicis

Answer 42

Posterior surface of distal third of ulna and interosseous membrane

Question 43

Insertion of extensor indicis

Answer 43

Extensor expansion of 2nd finger

Question 44

Innervation of extensor indicis

Answer 44

Posterior interosseous nerve (c7 and c8), continuation of deep branch of radial nerve

Question 45

Actions of extensor indicis

Answer 45

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