Posterior Compartment of the Forearm

Question 1

Name the 6 muscles in the superficial layer of the posterior forearm

Answer 1

Brachioradialis 
Extensor Carpi Radialis Longus 
Extensor Caripi Radialis Brevis 
Extensor Digitorum 
Extensor Digiti Minimi
Extensor Carpi Ulnaris

Question 2

Brachioradialis

origin, insertion, action

Answer 2

Origin - Lateral supracondylar ridge of humerus & adjacent IMS
Insertion - Lateral distal surface of radius
A - flexes forearm in mid prone position

Question 3

Extensor Carpi Radialis Longus

origin, insertion, action

Answer 3

Origin - Lateral supracondylar ridge of humerus and adjacent IMS
Insertion - Base of the second metacarpal
Action - Extension of the wrist, radial deviation

Question 4

Extensor Carpi Radialis Brevis

origin, insertion, action

Answer 4

Origin - Lateral epicondyle of humerous and adjacent IMS
Insertion - Base of the third metacrapal
Action - Extension of the wrist, radial deviation

Question 5

Extensor Digitorum

origin, insertion, action

Answer 5

Origin - Lateral epicondyle of humerus, adjacent IMS
Insertion - Middle and distal phangeals digits 2-5
Action - Extension of DIPS, PIPs, MCPs 2-5, extension of wrist

Question 6

Extensor Digiti Minimi

origin, insertion, action

Answer 6

Origin - Lateral epicondyle of humerus and adjacent IMS
Insertion - Extensor Expansion 5th digit
Action - Extension of MCP 5th digit

Question 7

Extensor Carpi Ulnaris

origin, insertion, action

Answer 7

Origin - Lateral epicondyle of humerus and adjacent IMS
Insertion - Base of 5th metacarpal
Action - Extension of wrist, ulnar deviation

Question 8

Name the 5 muscles in the deep layer or the forearms posterior compartment

Answer 8

Supinator 
Abductor Pollicis Longus
Extensor Pollicis Brevis
Extensor Pollicis Longus 
Extensor Indicis

Question 9

Supinator

origin, insertion, action

Answer 9

Origin - 2 heads:
Superficial head: Lateral epicondyle & radial colateral and annular ligament
Deep head: Spinator crest on Ulna
Insertion - Proximal 1/3 of lateral surface of radius
Action - Supernation

Question 10

Abduction Pollicis Longus

origin, insertion, action

Answer 10

Origin - Proximal 1/3 of radius and ulna, interosseous membrane
Insertion - Base of metacarpal 1st digit
Action - abduction of 1st digit

Question 11

Extensor Pollicis Brevis

origin, insertion, action

Answer 11

Origin - Distal 3rd, posterior surface of radius, interosseous membrane
Insertion - Base of proximal phalage 1st digit
Action - extends MCP and CMC of 1st digit

Question 12

Extensor Pollicis Longus

origin, insertion, action

Answer 12

Origin - Middle of the posterior surface of ulna, interosseous membrane
Insertion - distal phalanx 1st digit
Action - Extends IP, MCP, CMC of 1st digit