Posterior Compartment of Forearm

Question 1

extensor carpi radialis longus (ECRL) prox attach

Answer 1

lateral supracondylar ridge

Question 2

extensor carpi radialis longus (ECRL) distal attach

Answer 2

dorsal aspect of base of 2nd metacarpal

Question 3

extensor carpi radialis longus (ECRL) axn

Answer 3

wrist extension, radial deviation (abd)

Question 4

extensor carpi radialis longus (ECRL) innervation

Answer 4

radial n. (C6, C7)

Question 5

extensor carpi radialis brevis (ECRB) prox attach

Answer 5

lateral epicondyle

Question 6

extensor carpi radialis brevis (ECRB) distal attach

Answer 6

base of dorsal aspect of 3rd metacarpal

Question 7

extensor carpi radialis brevis (ECRB) axn

Answer 7

wrist extension, radial deviation (abd)

Question 8

extensor carpi radialis brevis (ECRB) innervation

Answer 8

deep branch of radial n (C7*, C8)

Question 9

extensor carpi ulnaris (ECU) prox attach

Answer 9

lateral epicondyle of humerus and posterior border of ulna

Question 10

extensor carpi ulnaris (ECU) distal attach

Answer 10

base of dorsal aspect on 5th metacarpal bone

Question 11

extensor carpi ulnaris (ECU) axn

Answer 11

wrist ext, ulnar deviation

Question 12

extensor carpi ulnaris (ECU) innervation

Answer 12

posterior interosseous n. (PIN) (branch of radial) (C7*, C8)

Question 13

extensor digitorum (ED) prox attach

Answer 13

lateral epicondyle of humerus

Question 14

extensor digitorum (ED) distal attach

Answer 14

extensor expansions of medial four digits (central slip to base of middle phalanx; distal terminal insertion to base of distal phalanx)

Question 15

extensor digitorum (ED) axn

Answer 15

primary: extension at MCP, wrist ext
secondary: ext at PIP and DIP

Question 16

extensor digitorum (ED) innervation

Answer 16

PIN (C7*, C8)

Question 17

extensor indicis prox attach

Answer 17

posterior surface of distal 1/3 of ulna and interosseous membrane

Question 18

extensor indicis distal attach

Answer 18

extensor expansion (hood mechanism) of 2nd digit

Question 19

extensor indicis axn

Answer 19

extends 2nd digit (especially at PIP)
secondary: wrist ext

Question 20

extensor indicis innervation

Answer 20

PIN (C7, C8*)

Question 21

extensor digiti minimi prox attach

Answer 21

lateral epicondyle of humerus

Question 22

extensor digiti minimi distal attach

Answer 22

extensor expansion of 5th digit

Question 23

extensor digiti minimi axn

Answer 23

extends 5th digit at MCP, PIP, DIP
secondary: wrist extension

Question 24

extensor digiti minimi innervation

Answer 24

PIN (C7*, C8)

Question 25

abductor pollicis longus prox attach

Answer 25

posterior surfaces of ulna, radius, and interosseous membrane

Question 26

abductor pollicis longus distal attach

Answer 26

base of 1st metacarpal bone

Question 27

abductor pollicis longus axn

Answer 27

abduct thumb at CMC
secondary: extends thumb at CMC

Question 28

abductor pollicis longus innervation

Answer 28

PIN (C7, C8*)

Question 29

extensor pollicis brevis (EPB) prox attach

Answer 29

posterior surface of distal 1/3 of radius and interosseous membrane

Question 30

extensor pollicis brevis (EPB) distal attach

Answer 30

dorsal aspect of base of proximal phalanx of thumb

Question 31

extensor pollicis brevis (EPB) axn

Answer 31

extends MCP of thumb and extends metacarpal at CMC

Question 32

extensor pollicis brevis (EPB) innervation

Answer 32

PIN (C7, C8*)

Question 33

extensor pollicis longus (epl) prox attach

Answer 33

posterior surface of middle third of ulna and interosseous membrane

Question 34

extensor pollicis longus (epl) distal attach

Answer 34

dorsal aspect of base of distal phalanx of thumb

Question 35

extensor pollicis longus (epl) axn

Answer 35

extends distal phalanx of thumb at IP
secondary: extends MCP and CMC of thumb
*can adduct thumb if IP extended and laterally rotate thumb

Question 36

extensor pollicis longus (epl) innervation

Answer 36

PIN (C7, C8*)