Posterior Compartment

Question 1

Brachioradialis

Answer 1

O: proximal 2/3 of lateral supraepicondylar ridge of humerus
I: lateral surface of distal end of radius proximal to styloid process
A: flexes forearm
IN: Radial n. (C5, C6, C7)

Question 2

Extensor Carpi Radialis Longus

Answer 2

O: lateral supracondylar ridge of humerus
I: base of 2nd metacarpal
A: extends and abducts wrist
IN: Radial n. (C6-C7)

Question 3

Extensor Carpi Radialis Brevis

Answer 3

O: lateral epicondyle of humerus
I: base of 3rd metacarpal
A: extends and abducts wrist
IN: deep branch of radial n. (C7-C8)

Question 4

Extensor Digitorum

Answer 4

O: lateral epicondyle of humerus
I: extensor expansion of digits 2-5
A: extends digits 2-5 at MCP, PIP and DIP joints; extends wrist
IN: posterior interosseus n. (C7-C8)

Question 5

Extensor Digiti Minimi

Answer 5

O: lateral epicondyle of humerus
I: extensor expansion of 5th digit
A: extends digit 5 at MCP, PIP, and DIP joints; extends wrist
IN: posterior interosseus n. (C7-C8)

Question 6

Extensor Carpi Ulnaris

Answer 6

O: lateral epicondyle and posterior border of ulna
I: base of 5th metacarpal
A: extension and ulnar deviation of wrist
IN: posterior interosseus n. (C7-C8)

Question 7

Anconeus

Answer 7

O: lateral epicondyle of humerus
I: lateral surface of olecranon + superior part of posterior surface of ulna
A: assists triceps in extending elbow; abducts ulna during pronation
IN: radial n.(C7, C8, T1)

Question 8

Supination

Answer 8

O: lateral epicondyle, radial collateral + annular ligament, supinator fossa and crest
I: lateral, posterior, anterior surfaces of proximal 1/3 of radius
A: supinates forearm
IN: deep branch of radial n. (C7-C8)

Question 9

Abductor Pollicis Longus

Answer 9

O: posterior surfaces of ulna + radius, interosseus membrane
I: base of 1st metacarpal
A: abducts and extends thumb at CMC joint
IN: posterior interosseus n. (C7-C8)

Question 10

Extensor Pollicis Brevis

Answer 10

O: posterior surface of radius and interosseus membrane
I: base of proximal phalanx of thumb via extensor expansion
A: extends thumb at MCP joint
IN: posterior interosseus n.(C7-C8)

Question 11

Extensor Pollicis Longus

Answer 11

O: posterior surface of ulna and interosseus membrane
I: base of distal phalanx of thumb via extensor expansion
A: extends thumb at DIP joint and MCP joint
IN: posterior interosseus n. (C7-C8)

Question 12

Extensor Indicis

Answer 12

O: posterior surface of ulna and interosseus membrane
I: extensor expansion of 2nd digit
A: extends index finger independently; assists wrist extension
IN: posterior interosseus n. (C7-C8)