Muscles of the Posterior Forearm-Deep Layer

Question 1

supinator

Answer 1

origin: radius, ulna and interosseous membrane
insertion: radius
innervation: deep radial n.
action: supination

Question 2

abductor pollicis longus

Answer 2

origin: radius, ulna and interosseous membrane
insertion: base 1st metacarpal
innervation: posterior interosseous n.
action: abduction of the thumb

Question 3

extensor pollicis brevis

Answer 3

origin: radius, ulna and interosseous membrane
insertion: base of the proximal phalanx of the thumb
innervation: posterior interosseous n.
action: extension of the thumb

Question 4

extensor pollicis longus

Answer 4

origin: radius, ulna and interosseous membrane
insertion: base of the distal phalanx of the thumb
innervation: posterior interosseous n.
action: extension of the thumb

Question 5

extensor indicis

Answer 5

origin: radius, ulna and interosseous membrane
insertion: extensor expansion of digit 2
innervation: posterior interosseous n.
action: extension of the MP joint of digit 2