Posterior Forearm Muscles

Question 1

O: Lateral epicondyle of the humerus via the CET, and the posterior middle 1/3 of the ulna
I: Posterior side of the base of the fifth metacarpal, of the posterior hand on the ulnar side
A: Extends the hand at the wrist joint
Ulnar deviates the hand at the wrist joint

Answer 1

Extensor Carpi Ulnaris

Question 2

O: Lateral epicondyle of the humerus via the CET
I: Posterior side of the base of the third metacarpal, of the posterior hand on the radial side
A: Extends the hand at the wrist joint
Radially deviates the hand at the wrist joint

Answer 2

Extensor Carpi Radialis Brevis

Question 3

O: The distal 1/3 of the lateral supracondylar ridge of the humerus
I: Posterior side of the base of the second metacarpal, of the posterior hand on the Radial side
A: Extends the hand at the wrist joint
Radially deviates the hand at the wrist joint

Answer 3

Extensor Carpi Radialis Longus

Question 4

O: Distal 1/3 and interosseous membrane of the posterior ulna
I: Ulnar side of extensor digitorum, to attach to the middle, and distal phalanges of the second digit via dorsal digital expansion
A: Extends the index finger at the mcp, pip, and dip joints
Extensive hand at the wrist joint

Answer 4

Extensor Indicis

Question 5

O: Lateral epicondyle of the humerus via the CET
I: Phalanges of fingers 2-5, via its dorsal digital expansion onto the posterior surfaces of the middle and distal phalanges
A: Extends fingers 2-5 at the mcp, pip, and dip joints
Extends the hand at the wrist joint

Answer 5

Extensor Digitorum

Question 6

O: Distal 1/3 and the adjacent interosseous membrane of the posterior radius
I: The posterolateral base of the proximal phalanx of the thumb
A: Extends the thumb at the CMC and MCP joints
Abducts the thumb at the CMC joint

Answer 6

Extensor Pollicis Brevis

Question 7

O: Middle 1/3 and the adjacent interosseous membrane of the posterior ulna
I: Thumb, via its dorsal digital expansion onto the posterior surface of the distal phalanx of the thumb
A: Extends the thumb at the cmc, mcp, and IP joints

Answer 7

Extensor Pollicis Longus

Question 8

O: Lateral epicondyle of the humerus via the CET
I: Ulnar side of extensor digitorum tendon to attach to the middle and distal phalanges of the 5th digit via dorsal digital expansion
A: Extends the little finger at the mcp, pip, and dip joints
Extends the hand at the wrist joint

Answer 8

Extensor Digiti Minimi

Question 9

O: Posterior 1/3 of middle surface of radius and ulna, and interosseous membrane
I: Base of the first metacarpal
A: Abducts the thumb at the CMC joint
Extends the thumb at the CMC joint

Answer 9

Abductor Pollicis Longus