4 Muscles of the hand and wrist

Question 1

What are the muscles of the posterior forearm known as?

Answer 1

Extensor muscles

Question 2

Which nerve innervates the muscles of the posterior forearm?

Answer 2

The radial nerve

Question 3

What are the anatomical groups of the posterior muscles of the forearm?

Answer 3

Superficial muscles
Deep muscles

Question 4

What are the functional groups of the posterior muscles of the forearm?

Answer 4

Muscles which extend abduct/adduct the hand at the wrist
Muscles which extend the medial four fingers
Muscles which extend the thumb

Question 5

What are the three muscles which extend and abduct/adduct the hand at the wrist joint?

Answer 5

Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris

Question 6

Where are the extensor carpi radialis longus in the forearm?

Answer 6

Posterior superficially, laterally
From supracondylar ridge of humerus to Metacarpal II and III

Question 7

What is the function of the extensor carpi radialis longus?

Answer 7

Extension of the wrist
Abduction of the wrist

Question 8

What is the innervation of the extensor carpi radialis longus?

Answer 8

Radial nerve

Question 9

Where are the extensor carpi radialis brevis in the forearm?

Answer 9

Posterior superficial, laterally
From lateral epicondyle of the humerus to Metacarpal II and III

Question 10

What is the function of the extensor carpi radialis brevis?

Answer 10

Extension of the wrist
Abduction of the wrist

Question 11

What is the innervation of the extensor carpi radialis brevis?

Answer 11

Radial nerve

Question 12

Where are the extensor carpi ulnaris in the forearm?

Answer 12

Posterior superficial, medially
From lateral epicondyle of humerus to base of Metacarpal V

Question 13

What is the function of the extensor carpi ulnaris?

Answer 13

Extension at the wrist
Adduction of the wrist

Question 14

What is the innervation of the extensor carpi radialis brevis?

Answer 14

Radial nerve

Question 15

Which muscle in the anterior compartment of the forearm helps extensor carpi radialis longus/brevis with abduction of the wrist?

Answer 15

Flexor carpi radialis

Question 16

Where is the extensor digitorum in the forearm?

Answer 16

Posterior superficial,
From lateral epicondyle of humerus then passes under extensor retinaculum and splits into four tendons attaching to extensor hoods of fingers

Question 17

What is the innervation of the extensor digitorum?

Answer 17

Deep brances of radial nerve

Question 18

What is the function of the extensor digitorum?

Answer 18

Main extensor of fingers at MCP and IP joints

Question 19

How do you test the function of extensor digitorum?

Answer 19

Pronate forearm and extend fingers against resistance

Question 20

Where is the extensor incidus proprius in the forearm?

Answer 20

Posterior, deep
From posterior surface of the ulna and interosseus membrane (distal to EPL) to extensor hood of index finger

Question 21

What is the function of the extensor incidus proprius?

Answer 21

Allows index finger to be independent of other digits in extension
Extension of index finger

Question 22

What is the innervation of the extensor incidus proprius?

Answer 22

Posterior interosseous branch of radial nerve

Question 23

Where is the extensor digiti minimi in the forearm?

Answer 23

Posterior, superficial
From lateral epicondyle of humeus to extensor hood of little finger (medial to extensor digitorum)

Question 24

What is the function of the extensor incidus proprius?

Answer 24

Extension of little finger
Contributes to the extension of the wrist

Question 25

What is the innervation of the extensor incidus proprius?

Answer 25

Deep branch of radial nerve

Question 26

What are the three muscles which extend or abduct the thumb?

Answer 26

Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus

Question 27

Where is the abductor pollicis longus in the forearm?

Answer 27

Posterior deep, immediatley distal to supinator muscle
From interosseous membrane adjecent posterior surface of radius and ulna to lateral part of base of metacarpal I

Question 28

What is the function of the abductor pollicis longus?

Answer 28

Abduction of the thumb

Question 29

What is the innervation of the abductor pollicis longus?

Answer 29

Posterior interosseous branch of radial nerve

Question 30

Where is the extensor pollicis brevis in the forearm?

Answer 30

Posterior, deep (medial and deeper than abductor pollicus longus)
From posterior surface of radius and interosseous membrane to base of proximal phalanx of the thumb

Question 31

What is the function of the extensor pollicis brevis?

Answer 31

Extension of MCP joint of thumb
Extension of carpometacarpal joints of thumb

Question 32

What is the innervation of the extensor pollicis brevis?

Answer 32

Posterior interosseous branch of the radial nerve

Question 33

Where is the extensor pollicis longus in the forearm?

Answer 33

Posterior deep, medial to dorsal tubercle
From posterior surface of ulna and interosseous membrane to distal phalanx of the thumb

Question 34

What is the function of the extensor pollicus longus?

Answer 34

Extension of all joints of the thumb
Carpometacarpal
Metacarpophalangeal
Interphalangeal

Question 35

What is the innervation of the extensor pollicus longus?

Answer 35

Posterior interosseus branch of radial nerve

Question 36

Where is the supinator muscle located?

Answer 36

In floor of cubital fossa (inside of elbow)

Question 37

How many heads does the supinator muscle have?

Answer 37

2 with deep branch of radial nerve passing between them

Question 38

Where is the supinator muscle attached?

Answer 38

From lateral epicondyle of humerus and posterior surface of ulna to posterior surface of the radius

Question 39

What is the function of the supinator muscle?

Answer 39

Supination of the forearm

Question 40

What is the innervation of the supinator muscle

Answer 40

Deep branch of radial nerve