posterior forearm muscles OIA

Question 1

brachioradialis

Answer 1

O: proximal 2/3 of lateral supracondylar ridge
I: styloid process of radius
A: flexion of forearm @ elbow, pronation/supination of forearm @ RU joints - arm starting in neutral position

Question 2

extensor carpi radialis longus

Answer 2

O: lateral supracondylar ridge (distal 1/3 of humerus)
I: base of 2nd metacarpal (dorsal side)
A: extension, radial deviation of hand @ wrist. weak flexion of forearm @ elbow, weak pronation/supination of forearm @ RU

Question 3

extensor carpi radialis brevis

Answer 3

O: lateral epicondyle
I: base of 3rd metacarpal (dorsal side)
A: extension, radial deviation of hand @ wrist. weak flexion of forearm @ elbow, weak pronation/supination of forearm @ RU (only to return to neutral position)

Question 4

extensor digitorum

Answer 4

O: lateral epicondyle
I: posterior surfaces of distal phalanges of fingers 2-5 via dorsal digital expansion
A: extension of fingers 2-5 @ MCP, PIP, DIP, extension of hand @ wrist. weak medial rotation of 5th finger @ CMC. weak extension of forearm @ elbow

Question 5

extensor carpi ulnaris

Answer 5

O: lateral epicondyle, posterior middle 1/3 of ulna
I: posterior base of 5th metacarpal
A: extension, ulnar deviation of hand @ wrist. weak extension of forearm @ elbow, weak pronation of hand @ proximal RU joint.

Question 6

anconeus

Answer 6

O: lateral epicondyle
I: lateral side of proximal olecranon process, posterior 1/4 of ulna
A: extension of forearm @ elbow

Question 7

supinator

Answer 7

O: lateral epicondyle, supinator crest (proximal ulna)
I: proximal 1/3 of radius (posterior, lateral, anterior sides)
A: supination of forearm @ RU

Question 8

extensor pollicis longus

Answer 8

O: posterior ulna and interosseous membrane (middle 1/3)
I: base of distal phalange of thumb (dorsal surface)
A: extension of thumb @ CMC, MCP, IP joints. weak lateral rotation, adduction of thumb @ CMC joint. weak extension/radial deviation of hand @ wrist. weak supination of forearm @ RU

Question 9

extensor pollicis brevis

Answer 9

O: posterior radius and interosseous membrane (distal 1/3)
I: base of proximal phalange of thumb (dorsal side)
A: extension of thumb @ CMC, MCP joints. abduction of thumb @ CMC. weak lateral rotation of thumb @ CMC. weak radial deviation of hand @ wrist

Question 10

abductor pollicis longus

Answer 10

O: posterior radius/ulna/interosseous membrane (middle 1/3)
I: base of 1st metacarpal (lateral side)
A: abduction, extension of thumb @ CMC. weak lateral rotation of thumb @ CMC. weak radial deviation, flexion of hand @ wrist. weak supination of forearm @ RU.

Question 11

extensor indicis

Answer 11

O: distal ulna and interosseous membrane (middle 1/3)
I: dorsal middle and distal phalanges of index finger
A: extension of index finger @ MCP, PIP, DIP joints. extension of hand @ wrist. weak adduction of index finger @ MCP. weak supination of forearm @ RU.