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MSK > Week 5 > Flashcards

Week 5 Flashcards

1
Q

Name the superficial and deep muscles in the posterior compartment of the forearm

A

Superficial: brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, anconeusDeep: supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis

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2
Q

When is the brachioradialis most visible?

A

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

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3
Q

What is the action of the brachioradialis? Why is this of interest?

A

It produces flexion at the elbow, but as its origin and innervation are characteristic of an extensor muscle, it is classified in the extensor compartment

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4
Q

What is the innervation of the brachioradialis?

A

Radial nerve

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5
Q

Where are the extensor carpi radialis longus and extensor carpi radialis brevis found?

A

Laterally in the posterior forearm, the brevis lies deep to the longus

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6
Q

Where do the extensor carpi radialis longus and brevis attach?

A

II (longus) and III (brevis) metacarpal bones

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7
Q

What is the innervation of the extensor carpi radialis longus and brevis?

A

Radial nerve

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8
Q

What is the main extensor of the fingers?

A

The extensor digitorum; it makes up most of the posterior surface of the forearm

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9
Q

What is the action of the extensor digitorum?

A

Extension of the medial four fingers at the metacarpalpholangeal and interphalangeal joints of the hand

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10
Q

What is the innervation of the extensor digitorum?

A

Radial nerve

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11
Q

Describe the location of the extensor digiti minimi relative to the extensor digitorum

A

Medially, slightly deep

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12
Q

What is the action of the extensor digiti minimi?

A

Acts to extend the little finger, and also contributes to extension at the wrist

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13
Q

What is the innervation of the extensor digiti minimi?

A

Radial nerve

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14
Q

Where is the extensor carpi ulnaris found in the forearm

A

Posterior, medial

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15
Q

Where does the extensor carpi ulnaris attach?

A

The base of metacarpal V

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16
Q

What is the action of the extensor carpi ulnaris? What is its innervation?

A

Extends and adducts the wrist; the radial nerve

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17
Q

Which muscle is most medial of those in the extensor compartment of the forearm?

A

The anconeus

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18
Q

Which other muscle can it be hard to distinguish the anconeus from?

A

The anconeus is blended with the fibres of the triceps brachii

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19
Q

What is the action of the anconeus? What is its innervation?

A

Acts to move the ulna during pronation and extends at the elbow joint; radial nerve

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20
Q

What is wrist drop a characteristic sign of?

A

Radial nerve injury in the axilla or radial groove

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21
Q

What happens in wrist drop?

A

No radial innervation of extensors at wrist; they are paralysed. Unnoposed flexion (wrist drop) occurs due to action of flexor muscles (median nerve)

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22
Q

What is the action of the supinator? What is its innervation?

A

Supinates the forearm; radial nerve

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23
Q

Which border of the anatomical snuffbox does the abductor pollicis longus contribute to?

A

Lateral border

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24
Q

Describe the location of the abductor pollicis longus

A

Distal to the supinator on the lateral side of the forearm

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25
Q

What is the action of the abductor pollicis longus? What is its innervation?

A

Abducts the thumb; radial nerve

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26
Q

What is the position of the extensor pollicis brevis relative to the abductor pollicis longus?

A

Medial

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27
Q

Apart from the abductor pollicis longus, which muscle makes up most of the lateral border of the anatomical snuffbox?

A

Extensor pollicis brevis

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28
Q

What is the action of the extensor pollicis brevis? What is its innervation?

A

Extend the metacarpophlanageal and carpometacarpal joints of the thumb; radial nerve

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29
Q

What is the action of the extensor pollicis longus? What is its innervation?

A

Extends all the joints of the thumb; radial nerve

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30
Q

What is the action of the extensor indices? Why is it important?

A

Extends the index finger; allows the index finger to be independent of the other fingers during extension

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31
Q

What is the innervation of the extensor indices?

A

Radial nerve

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32
Q

What type of joints are the radioulnar joints? What movement do they allow?

A

They are both synovial pivots, responsible for the pronation and supination of the forearm

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33
Q

What is the proximal radioulnar joint formed by?

A

The head of the radius, articulating with the radial notch of the ulna

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34
Q

Which ligament keeps the radius in place at the proximal radioulnar joint?

A

The anular radial ligament; it forms a collar around the joint

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35
Q

Which muscles produce pronation at the radioulnar joints?

A

The pronator teres and pronator quadratus

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36
Q

Which muscles produce supination at the radioulnar joints?

A

The biceps brachii, and the supinator

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37
Q

What is the distal radioulnar joint formed by?

A

The head of the ulnar and the ulnar notch on the medial side of the radius

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38
Q

Which ligaments strengthen the distal radioulnar joint?

A

The anterior (palmar radioulnar) and posterior (dorsal radioulnar) ligaments, and the articular ligament

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39
Q

What are the functions of the articular ligament at the distal radioulnar joint?

A

It binds the radius and ulna together, holding them together during movement of the joint; it separates the distal radioulnar joint from the wrist joint

40
Q

What is the anatomical snuffbox?

A

Triangular depression found on the lateral aspect of the dorsum of the hand, at the level of the carpal bones

41
Q

What is the lateral border of the anatomical snuffbox?

A

Tendons of the abductor pollicis longus and extensor pollicis brevis

42
Q

Which structure is of importance in the anatomical snuffbox?

A

The radial nerve; it passes diagonally through the anatomical snuffbox on its path into the hand

43
Q

What is the medial border of the anatomical snuffbox?

A

Tendon of the extensor pollicis longus

44
Q

What is the proximal border of the anatomical snuffbox?

A

Styloid process of the radius

45
Q

What is the base of the anatomical snuffbox?

A

Scaphoid and trapezium carpal bones

46
Q

What articulation occurs in the anatomical snuffbox?

A

Scaphoid and radius articulate to form part of the wrist joint

47
Q

Which bones articulate to form the wrist joint?

A

Distal end of radius, and proximal row of carpal bones (except pisiform)

48
Q

Which three general things contribute to the stability of the wrist joint?

A

Joint capsule, structure of the joint, and associated ligaments

49
Q

Describe the two layers of the wrist joint capsule

A

Fibrous outer layer attaches to the radius, ulna and proximal carpal bones; the internal layer is comprised of a synovial membrane, secreting synovial fluid which lubricates the joint

50
Q

At the wrist joint, which bony landmark prevents excessive abduction?

A

Styloid process of the radius

51
Q

Name the four important ligaments at the wrist joint

A

Palmar radiocarpal, dorsal radiocarpal, ulnar collateral, radial collateral

52
Q

Describe the structure and function of the palmar radiocarpal ligament

A

Found on the anterior side of the hand; passes from the radius to both rows of carpals; adds to stability and ensures hand follows forearm during supination

53
Q

Describe the structure and function of the dorsal radiocarpal ligament

A

Found on the posterior side of the hand; passes from the radius to both rows of carpals; contributes to stability and ensures that hand follows forearm during pronation

54
Q

Describe the location of the ulnar collateral ligament

A

Runs from the styloid process to the triquetrum

55
Q

Describe the location of the radial collateral ligament

A

Runs from the styloid process to the scaphoid

56
Q

What type of joint is the wrist joint? What movements does it allow?

A

Synovial ellipsoid; allows for movement along two axes (flexion /extension, adduction/abduction)

57
Q

Which muscles produce flexion at the wrist joint?

A

Mainly the flexor carpi radialis and flexor carpi ulnaris, with assistance from the flexor digitorum superficialis, flexor digitorum profundus and palmaris longus

58
Q

Which muscles produce extension at the wrist joint?

A

Mainly the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris, with assistance from the extensor digitorum, extensor pollicis longus and extensor indicis

59
Q

Which muscles produce adduction at the wrist joint?

A

Extensor carpi ulnaris and flexor carpi ulnaris

60
Q

Which muscles produce abduction at the wrist joint?

A

Abductor pollicis longus, flexor carpi radilias, extensor carpi radialis longus and brevis

61
Q

How can you suffer an anterior dislocation of the lunate? What can this cause?

A

Falling on a dorsiflexed wrist; can compress carpal tunnel, causing carpal tunnel syndrome. The lunate can also undergo avascular necrosis

62
Q

What will happen if there is damage to the radial nerve at the radial groove?

A

Wrist drop; (unopposed flexion), the radial nerve innervates the extensors. There will be some sensory loss over the dorsal (posterior) surface of the hand and the proximal ends of the lateral 3 and a half fingers dorsally

63
Q

What are the motor innervations and hence functions of the radial nerve?

A

Triceps brachii muscle (extension at elbow), posterior compartment of forearm (extension of wrist, and hand joints, and supination)

64
Q

What motor function loss occurs with damage to the radial nerve in the axilla?

A

Triceps and muscles in posterior compartment of forearm are paralysed; inability to extend at elbow, wrist, or fingers; unopposed flexion – wrist drop

65
Q

Why can supination still occur when the radial nerve is damaged?

A

Action of biceps brachii, innervated by the musculotaneous nerve

66
Q

What sensory loss will there be with damage to the radial nerve in the axilla?

A

Whole of cutaneous innervation of radial nerve; most of the back of the arm and hand

67
Q

How is the radial nerve most commonly damaged in the radial groove?

A

Midshaft humeral fracture

68
Q

Why is extension at the elbow still possible in patients with damage to the radial nerve in the radial groove?

A

Majority of branches have already arisen is the triceps brachii not paralysed with damage

69
Q

What motor function is lost with damage to the radial nerve in the radial groove?

A

Extension at the wrist and hand (muscles in posterior compartment paralysed), wristdrop occurs

70
Q

What sensory loss occurs with damage to the radial nerve in the radial groove?

A

Forearm cutaneous branches have already arisen, so there is only sensory loss on the dorsum of the hand

71
Q

How is the deep branch of the radial nerve in the forearm damaged?

A

Fractures of the radial head, or posterior dislocation of the radius at the elbow joint

72
Q

Which muscles of the posterior compartment are NOT damaged with damage to the deep branch of the radial nerve in the forearm?

A

Supinator and extensor carpi radialis longus; wristdrop will not occur (ECRL is a strong extensor)

73
Q

What sensory loss occurs with damage to the deep branch of the radial nerve in the forearm?

A

None, it is a motor nerve

74
Q

How is the superficial radial nerve commonly damaged in the forearm?

A

Stabbing/laceration

75
Q

What motor loss occurs with damage to the superficial radial nerve in the forearm?

A

None, it is a sensory nerve

76
Q

What type of joint is the elbow? Which actions can it perform?

A

Synovial hinge; extension and flexion

77
Q

Which muscles perform extension at the elbow joint?

A

Triceps brachii and anconeus

78
Q

Which muscles perform flexion at the elbow?

A

Brachialis, biceps brachii and brachioradialis

79
Q

What are the thickenings at the medial and lateral sides of the joint capsule? What purpose do they serve?

A

Collateral ligaments; stabilise the joint

80
Q

Describe the location of the radial collateral ligament of the elbow joint

A

Found on the lateral side, extending from the lateral epicondyle, and blending with the anular ligament

81
Q

Describe the location of the ulnar collateral ligament of the elbow

A

Originates from the medial epicondyle, attaches to coronoid process and olecranon of ulna

82
Q

Name the three important bursae of the elbow joint

A

Intratendinosus, subtendinous, subcutaneous

83
Q

Where is the intratendinous bursa of the elbow joint formed?

A

Within the tendons of the triceps brachii

84
Q

Where is the subtendinous bursa of the elbow joint found?

A

Between the olecranon and the tendon of the triceps brachii, reducing friction between the two structures during extension and flexion of the forearm

85
Q

Where is the subcutaneous bursa of the elbow joint found?

A

Between the olecranon and overlying connective tissue

86
Q

Describe subcutaneous bursitis of the elbow

A

Repeated friction and pressure causes the bursa to become inflamed; because it is relatively superficial it can also become infected and cause inflammation

87
Q

Describe subtendinous bursitis of the elbow

A

Caused by repeated flexion and extension of the forearm, commonly seen in assembly line workers; usually flexion is more painful because more pressure is put on the bursa

88
Q

How does dislocation of the elbow joint usually occur in young children?

A

Fall on hand with elbow flexed

89
Q

Describe what happened during an elbow dislocation in a young child. Where does the humerus go? Which ligament is usually torn? Which nerve is at risk?

A

Distal end of humerus driven through weakest part of the joint capsule, the anterior side; the ulnar collateral ligament is usually torn, and the ulnar nerve can be involved

90
Q

What is the most common direction of elbow dislocation?

A

Posterior (elbow dislocations named by position of ulna and radius, not humerus)

91
Q

What is ‘tennis elbow’?

A

Pain and inflammation in and around the lateral epicondyle, from the common extensor tendinous origin; an overuse strain

92
Q

What is ‘golfer’s elbow’?

A

Pain and inflammation in and around the medial epicondyle, from the common flexor tendinous origin; an overuse strain

93
Q

What is a ‘pulled’ elbow? Describe what happens

A

Subluxation or dislocation of the articulating surface of the bones forming the proximal radio-ulnar joint; the injury results when a person is lifted by the upper limb with the forearm in a pronated position; the pulling of the upper limb tears the distal attachment of the annular ligament (surrounding the radial head) where it is loosely attached to the neck of the radius; the radial head moves distally and out of the torn ligament

94
Q

Why is a ‘pulled’ elbow more common in children?

A

The radial head an annular ligament have not fully formed

95
Q

Why is supination more powerful than pronation?

A

Strength of the biceps brachii is greater than the pronators

96
Q

Which bony structure can be palpated around the elbow?

A

Medial and lateral epicondyles, olecranon process of ulna and head of radius

MSK (8 decks)

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