Posterior Forearm

Question 1

how many muscles are there in the superficial layer of the posterior compartment of the forearm?

Answer 1

6 (in sheffield, 7 in leicester - anconeus)

Question 2

which nerve innervates all muscles in the posterior forearm?

Answer 2

radial nerve

Question 3

what is the general action of the posterior compartment of the forearm?

Answer 3

extension

Question 4

where is the common extensor origin?

Answer 4

lateral epicondyle of the humerus

Question 5

which 4 muscles come off the common extensor origin?

Answer 5

extensor carpi radialis brevis
extensor digitorum
extensor carpi ulnaris
extensor digiti minimi

Question 6

what are the attachments of the brachioradialis?

Answer 6

humerus

distal radius

Question 7

what is the action of brachioradialis?

Answer 7

FLEXOR at elbow

Question 8

which aspect of the forearm do the ECRL and ECRB muscles run down? what action does this enable them to produce?

Answer 8

lateral aspect - abduction at wrist

Question 9

what is the action of extensor carpi radialis longus?

Answer 9

abduction and extension at wrist

Question 10

what is the action of extensor carpi radialis brevis?

Answer 10

abduction and extension at wrist

Question 11

which muscle is the main extensor of fingers (at MCP and IP!)

Answer 11

extensor digitorum

Question 12

what is the action of extensor digitorum?

Answer 12

extension of fingers at MCP and IP joints

Question 13

what are the attachments of extensor digitorum?

Answer 13

lateral epicondyle

extensor hood of each finger

Question 14

what are the attachments of extensor digiti minimi?

Answer 14

lateral epicondyle

extensor hood of little finger

Question 15

what is the action of extensor digiti minimi?

Answer 15

extends little finger

contributes to wrist extension

Question 16

along which aspect of forearm does extensor carpi ulnaris lie? what action does this position enable it to produce?

Answer 16

medial aspect

adduction at wrist

Question 17

what is the action of extensor carpi ulnaris?

Answer 17

adduction and extension at wrist

Question 18

name the 6 muscles of the superficial layer of the posterior compartment of the forearm?

Answer 18

brachioradialis
extensor carpi radialis longus + brevis
extensor digitorum
extensor digiti minimi
extensor carpi ulnaris

(bonus for leicester: anconeus)

Question 19

how many muscles are there in the deep layer of the posterior compartment of the forearm?

Answer 19

5

Question 20

how many muscles are there in the posterior forearm?

Answer 20

11 - 5 in deep, 6 in superficial

Question 21

which digits do most of the deep muscles of the posterior compartment of the forearm act upon?

Answer 21

thumb and index finger (all but supinator)

Question 22

where in the cubital fossa does the supinator lie?

Answer 22

the floor

Question 23

what structure passes between the two heads of the supinator?

Answer 23

deep branch of radial nerve

Question 24

what are the attachments of the supinator?

Answer 24

two heads: lateral epicondyle / posterior surface of ulna

attach to posterior surface of radius

Question 25

to which border of the anatomical snuffbox does the abductor pollicis longus tendon contribute?

Answer 25

lateral

Question 26

which tendons contribute to the lateral border of the anatomical snuffbox?

Answer 26

abductor pollicis longus and extensor pollicis brevis

Question 27

what is the action of abductor pollicis longus

Answer 27

abducts thumb

Question 28

to which border of the anatomical snuffbox does the extensor pollicis brevis tendon contribute?

Answer 28

lateral

Question 29

what is the action of the extensor pollicis brevis?

Answer 29

extends thumb at MCP + carpometacarpal joints of thumb

Question 30

to which border of the anatomical snuffbox does the extensor pollicis longus tendon contribute?

Answer 30

medial

Question 31

what is the action of the extensor pollicis longus?

Answer 31

extends all thumb joints - carpometacarpal, MCP and IP

Question 32

what is the action of extensor indicis?

Answer 32

extends index finger - allows independent movement of index finger when extended

Question 33

name the 5 muscles of the deep layer of the posterior compartment of the forearm

Answer 33

``` supinator abductor pollicis longus extensor pollicis brevis extensor pollicis longus extensor indicis ```