Week 9 - superficial posterior forearm muscles

Question 1

Superficial layer

Answer 1

Brachioradialis*
Extensor carpi radialis longus*
Extensor carpi radialis brevis *
Extensor digitorum*
Extensor digiti minimi*
Extensor carpi ulnaris*

Question 2

Deep layer

Answer 2

Supinator*
Abd. pollicis longus
Ext. pollicis brevis
Ext. pollicis longus
Extensor indicis

Question 3

BRACHIORADIALIS

Answer 3

Attachments:
P: proximal 2/3 of lateral supraepicondylar ridge of humerus
D: lateral distal radius

Action: elbow flexor (“drinker’s
muscle”)

NS: radial n.

Question 4

EXTENSOR CARPI RADIALIS LONGUS

Answer 4

Attachments:
P: lateral supra-epicondylar ridge of humerus
D: dorsal base of 2nd metacarpal

Action: wrist extension and radial deviation
(abduction)

NS: radial n.

Question 5

EXTENSOR CARPI RADIALIS BREVIS

Answer 5

Attachments:
P: lateral epicondyle of the humerus
D: dorsal base of 3rd metacarpal

Action: wrist extension and radial deviation

NS: (deep branch) of radial n.

Question 6

EXTENSOR DIGITORUM

Answer 6

Attachments:
P: lateral epicondyle of humerus
D: extensor expansions of digits 2-4
(more on this in the hand lecture)

Action: wrist, metacarpophalangeal
& interphalangeal joints extension

NS: (deep branch) of radial n.

Question 7

EXTENSOR DIGITI MINIMI

Answer 7

Attachments:
P: lateral epicondyle of humerus
D: extensor expansion of 5th digit

Action: wrist, metacarpophalageal
& interphalangeal joints extension

NS: (deep branch) of radial n.

Question 8

EXTENSOR CARPI ULNARIS

Answer 8

Attachments:
P: lateral epicondyle of humerus &
ulna
D: dorsal base of 5th metacarpal

Action: wrist extension and ulnar
deviation (adduction)

NS: (deep branch) of radial n.

Question 9

You palpate Dominic’s lateral elbow and find that he is
sore just distal to the bony prominence under your thumb.
What muscle do you suspect is generating pain?

1. Brachioradialis
2. ECRL
3. ECRB
4. Triceps
5. Anconeus

Answer 9

3

Question 10

You test the muscles by completing several isometric tests and
you find that resisting finger extension at the distal IPJ is sore, but
nothing else is. Which muscle do you suspect is generating pain?

1. Brachioradialis
2. ECRL
3. ECRB
4. Extensor digitorum
5. Extensor carpi ulnaris

Answer 10

4