Forearm extensors (action and innervation)

Question 1

brachioradialis nerve innervation

Answer 1

Radial nerve (C5, C6, C7)

Question 2

brachioradialis action

Answer 2

relatively weak flexion of forearm

maximal when forearm is in mid-pronated position

Question 3

ECRL nerve innervation

Answer 3

radial nerve (C6, C7)

Question 4

ECRL action

Answer 4

extend and abduct hand at the wrist joint

ECRL active during fist clenching

Question 5

ECRB nerve innervation

Answer 5

deep branch of radial nerve (C7, C8)

Question 6

ECRB action

Answer 6

extend and abduct hand at the wrist joint

Question 7

what are the superficial layer muscle extensors

Answer 7

Brachioradialis, ECRL, ECRB, Extensor digitorum, EDM, ECU

Question 8

Extensor digitorum action

Answer 8

extends medial four digits primarily at metacarpophalangeal joints
secondarily at interphalangeal joints

Question 9

Extensor digitorum nerve innervation

Answer 9

deep branch of radial nerve (C7, C8)

Question 10

EDM action

Answer 10

extends 5th digit at MCPJ

secondary at IPJ

Question 11

EDM innervation

Answer 11

deep branch of radial nerve (C7, C8)

Question 12

ECU nerve innervation

Answer 12

deep branch of radial nerve (C7, C8)

Question 13

muscles that are innervated by deep branch of radial nerve (C7,C8)

Answer 13

ECRB, Extensor digitorum, EDM, ECU, supinator

Question 14

ECU action

Answer 14

extends and adducts hand at wrist joint (also active during fist clenching)

Question 15

what are the deep layer flexor muscles

Answer 15

supinator, extensor pollicis longus, extensor indicus, APL, EPOB

Question 16

supinator nerve innervation

Answer 16

deep branch of radial nerve C7 and C8

Question 17

supinator action

Answer 17

supinates forearm

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

Question 18

extensor indicis action

Answer 18

extends 2nd digits (enable independent extension)

helps extend hand at wrist

Question 19

APL nerve innervation

Answer 19

posterior interosseus nerve (C7, C8) - continuation of deep branch of radial nerve

Question 20

APL action

Answer 20

abducts thumb and extends it at carpometacarpal joint

Question 21

EPL action

Answer 21

extends distal phalanx of thumb at IPJ

extends MCP and CMC joints

Question 22

EPL nerve innervation

Answer 22

posterior interosseus nerve (C7, C8) - continuation of deep branch of radial nerve

Question 23

EPB nerve innervation

Answer 23

posterior interosseus nerve (C7, C8) - continuation of deep branch of radial nerve

Question 24

EPB action

Answer 24

extends proximal phalanx of thumb at MCP joint

extends CMC joint