Muscles of the Posterior Forearm Flashcards Preview

ESA 2- Musculoskeletal System > Muscles of the Posterior Forearm > Flashcards

Flashcards in Muscles of the Posterior Forearm Deck (71):
1

What are the muscles in the posterior compartment of the forearm commonly known as?

The extensor muscles

2

What is the general function of the muscles of the posterior compartment of the forearm?

To produce extension at the wrist and fingers

3

What are the extensor muscles innervated by?

The radial nerve

4

What can the muscles of the posterior forearm be divided into?

Two layers, deep and superficial

5

What divides the layers of muscles in the posterior forearm?

A layer of fascia

6

How many muscles are in the superficial layer of the posterior forearm?

6

7

What are the muscles of the superficial layer of the posterior forearm?

Brachioradialis 
Extensor carpi radialis longus 
Extensor carpi radialis brevis 
Extensor digitorum 
Extensor digiti minimi 
Extensor carpi ulnaris

8

What muscles share a common tendinous origin at the lateral epicondyle?

Extensor carpi radialis longus 
Extensor digitorum 
Extensor digiti minimi 
Extensor carpi ulnaris

9

Why is the brachioradialis a paradoxical muscle?

Because its origin and innervation are characteristic of an extensor muscle, but its actually a flexor at the elbow

10

When is the brachioradialis most visible?

When the forearm is half pronated, and flexing elbow against resistance

11

Where are the radial artery and nerve found in the distal forearm?

Sandwiched between the brachioradialis and the deep flexor muscles

12

What is the innervation of the brachioradialis?

Radial nerve (C5, C6, C7)

13

What is the arterial supply of the brachioradialis?

Radial recurrent artery

14

What is the main action of the brachioradialis?

Relatively weak flexion of the forearm, maximal when the forearm is in mid-pronated position

15

Where are the extensor carpi radialis muscles situated?

On the lateral aspect of the posterior forearm

16

What are the extensor carpi radialis muscles able to do due to their position?

Produce abduction as well as extension at the wrist

17

What is the innervation of the ECRL?

Radial nerve (C6, C7)

18

What is the arterial supply of the ECRL?

Radial artery

19

What is the innervation of the ECRB?

Deep branch of radial nerve (C7, C8)

20

What is the arterial supply of the ECRB?

Radial artery

21

What is the main action of the extensor carpi radialis muscles?

Extend and abduct the hand at the wrist joint
ECRL active during fist clenching

22

How is the function of the extensor digitorum tested?

The forearm is pronated, and the fingers extended against resistance

23

What is the innervation of the extensor digitorum?

Deep branch of radial nerve (C7, C8)

24

What is the arterial supply of the extensor digitorum?

Recurrent interosseous artery 
Posterior interosseous artery

25

What is the action of the extensor digitorum?

Extends medial four digits primarily at metacarpophalangeal joints, secondarily at interphalangeal joints

26

What is true in some people regarding the extensor digiti minimi?

This muscle and the extensor digitorum muscle are fused together

27

Where does the extensor digiti minimi (EDM) lie?

Medially to the extensor digitorum

28

What is the innervation of the EDM?

Deep branch of radial nerve (C7, C8)

29

What is the arterial supply of the EDM?

Posterior interosseous artery

30

What is the main action of the EDM?

Extends 5th digit primarily at metacarpophalangeal joint, secondarily at interphalangeal joint

31

Where is the extensor carpi ulnaris (EDU) found?

On the medial aspect of the posterior forearm

32

What is the EDU able to do due to its position?

Produce adduction as well as extension at the wrist

33

What is the innervation of the ECU?

Deep branch of the radial nerve (C7, C8)

34

What is the arterial supply of the ECU?

Ulnar artery

35

What is the main action of the ECU?

Extends and adducts the hand at the wrist joint 
Active during fist clenching

36

What does lateral epicondylitis refer to?

Inflammation of the periosteum of the lateral epicondyle

37

What is the peak age of onset of lateral epicondylitis?

40-50 years

38

What is lateral epicondylitis caused by?

Repeated use of the superficial extensor muscles, which stains their common tendinous attachment of the lateral epicondyle

39

How many muscles are in the deep compartment of the posterior forearm?

5

40

What muscles are in the deep compartment of the posterior forearm?

Supinator 
Abductor pollicis longus 
Extensor pollicis brevis
Extensor pollicis longus 
Extensor indicis

41

What do the deep muscles of the posterior forearm do?

Act on the thumb and index finger, with the exception of the supinator

42

Where does the supinator lie?

On the floor of the cubital fossa

43

What does the supinator have?

Two heads

44

What passes between the two heads of the supinator?

The deep branch of the radial nerve

45

What is the innervation of the supinator?

Deep branch of radial nerve (C7, C8)

46

What is the arterial supply to the supinator?

Recurrent interosseous artery

47

What is the main action of the supinator?

Supinates forearm- rotates radius to turn palm anteriorly or superiorly (if elbow are flexed)

48

Where is the abductor pollicis longus?

Immediately distal to the supinator muscle

49

What does the tendon of the abdutor pollicis longus contribute to?

The lateral border of the anatomical snuffbox

50

What is the innervation of the APL?

Posterior interosseous nerve (C7, C8), a continuation of the deep branch of the radial nerve

51

What is the arterial supply of the APL?

Posterior interosseous artery

52

What is the main action of the APL?

Abducts the thumb and extends it at the carpometacarpal joint

53

Where can the extensor pollicis brevis be found?

Medially and deep to the abductor pollicis longus

54

What does the tendon of the EPB contribute to?

The lateral border of the anatomical snuffbox

55

What is the innervation of the EPB?

Posterior interosseous nerve (C7, C8), a continuation of the deep branch of the radial nerve

56

What is the arterial supply of the EPB?

Posterior interosseous artery

57

What is the main action of the EPB?

Extends proximal phalanx of thumb at metacarpophalgeal joint 
Extends carpometacarpal joint

58

How does the extensor pollicis longus different from the EPB?

It has a larger muscle belly

59

Where does the tendon of the EPL travel?

Medially to the dorsal tubercle at the wrist

60

What does the tendon of the EPL act to do?

Uses the dorsal tubercle as a ‘pulley’ to increase the force exerted

61

What does the tendon of the EPL form?

The medial border of the anatomical snuffbox

62

What is the innervation of the EPL?

Posterior interosseous nerve (C7, C8), a continuation of the deep branch of the radial nerve

63

What is the arterial supply of the EPL?

Posterior interosseous artery

64

What is the main action of the EPL?

Extends distal phalanx of thumb at interphalangeal joints
Extends metacarpophalangeal and carpometacarpal joints

65

What does the extensor indicis proprius allow?

The index finger to be independent of the other fingers during extension

66

What is the innervation of the EIP?

Posterior interosseous nerve (C7, C8), a continuation of the deep branch of the radial nerve

67

What is the arterial supply of the EIP?

Posterior interosseous artery

68

What is the main action of the EIP?

Extends 2nd digit (enabling independent extension)
Helps extend hand at wrist

69

What is wrist drop a sign of?

Radial nerve injury that has occurred proximal to the elbow

70

What are the common characteristic sites of damage with wrist drop?

Axilla 
Radial groove of humerus

71

What causes wrist drop?

The radial nerve innervates all muscles in the extensor compartment of the forearm. In the event of a radial nerve lesion, these muscles are paralysed. The muscles that flex the wrist are innervated by the median nerve, and thus are unaffected. The tone of the flexor muscles produces unopposed flexion at the wrist joint – wrist drop.