Week 9 - deep posterior forearm muscles

Question 1

Deep layer muscles

Answer 1

A. Supinator
E. Extensor indicis
B. Abductor pollicis longus
C. Extensor pollicis brevis
D. Extensor pollicis longus

Question 2

SUPINATOR

Answer 2

Attachments:
P: lateral epicondyle of humerus, radial collateral and anular ligaments, crest of ulna
D: lateral proximal radius

Action: supination of forearm

NS: (deep branch of) radial n.

Question 3

ABDUCTOR POLLICIS LONGUS

Answer 3

Attachments:
P: posterior ulna, radius, and IOM
D: base of 1st metacarpal

Action: carpometacarpal joint abduction and extension of 1st digit

NS: posterior interosseous nerve (radial n.)

Question 4

EXTENSOR POLLICIS BREVIS

Answer 4

Attachments:
P: posterior radius and IOM
D: dorsal base of proximal phalanx of 1st digit

Action: 1st digit (thumb) extension

NS: posterior interosseous nerve (radial n.)

Question 5

EXTENSOR POLLICIS LONGUS

Answer 5

Attachments:
P: posterior ulna and IOM
D: dorsal aspect of base of distal phalanx of 1st digit

Action: extension of 1st digit

NS: posterior interosseous nerve (radial n.)

Question 6

EXTENSOR INDICIS

Answer 6

Attachments:
P: posterior ulna and IOM
D: extensor expansion of 2nd digit

Action: extension of 2nd digit

NS: posterior interosseous nerve (radial n.)

Question 7

Dominic has pain in the common extensor origin on
palpation. You expect him to be sore with isometric testing of
thumb muscles.

1. True
2. False

Answer 7

2. False