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MSK Exam II > Posterior Forearm > Flashcards

Posterior Forearm Flashcards

1
Q

What nerves provide cutaneous innervation to the posterior forearm?

A 
Supraclavicular nn.
Axillary n.
Radial n.
Medial brachial cutaneous n.
Medial antebrachial cutaneous n.
Intercostobrachial n.
Ulnar n. 
Proper palmar digital nn. (Median n.)
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2
Q

What 6 muscles are present in the superficial group of the posterior forearm?

A 
Brachioradialis m.
Extensor carpi radialis longus m.
Extensor carpi radialis brevis m.
Extensor digitorum longus m.
Extensor digiti minimi m.
Extensor carpi ulnaris m.
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3
Q

What 4 muscles are present in the deep group of the posterior forearm?

A

Supinator m.
Abductor pollicis longus m.
Extensor pollicis longus m.
Extensor indicis m.

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4
Q

ALL muscles of the posterior forearm are innervated by what nerve?

A

Radial n.

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5
Q

ALL muscles of the posterior forearm are innervated by the radial n. via what branches?

A

Deep branch or posterior interosseous nerve branch

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6
Q

Origin of brachioradialis m.

A

Supraepicondylar ridge of humerus

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7
Q

Insertion of brachioradialis m.

A

Lateral distal radius, proximal styloid process

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8
Q

Action of brachioradialis m.

A

Weak arm flexion; maximal when mid-pronated

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9
Q

Innervation of brachioradialis m.

A

Superficial branch of radial n.

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10
Q

Origin of extensor carpi radialis longus

A

Lateral supraepicondylar ridge of humerus

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11
Q

Insertion of extensor carpi radialis longus m.

A

Dorsal side of 2nd metacarpal

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12
Q

Action of extensor carpi radialis longus m.

A

Extends/abducts hand at wrist

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13
Q

Origin of extensor carpi radialis brevis m.

A

Lateral epicondyle of humerus

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14
Q

Insertion of extensor carpi radialis brevis m.

A

Dorsal base of 3rd metacarpal

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15
Q

Action of extensor carpi radialis brevis m.

A

Extends/abducts hand at wrist (same as extensor carpi radialis longus m.)

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16
Q

Origin of extensor carpi ulnaris m.

A

Lateral epicondyle; posterior ulna via shared aponeurosis

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17
Q

Insertion of extensor carpi ulnaris m.

A

Dorsal base of 5th metatarsal

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18
Q

Action of extensor carpi ulnaris m.

A

Extends and adducts hand at wrist

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19
Q

Origin of extensor digitorum m.

A

Lateral epicondyle

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20
Q

Insertion of extensor digitorum m.

A

Extensor expansion of medial 4 digits

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21
Q

Action of extensor digitorum m.

A

Extends primarily at MPJ, but also at IPJ

[also has some wrist extension function]

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22
Q

Origin of extensor digiti minimi m.

A

Lateral epicondyle

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23
Q

Insertion of extensor digiti minimi m.

A

Extensor expansion of 5th digit

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24
Q

Action of extensor digiti minimi m.

A

Extends 5th digit at MPJ but also at IPJ

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25
Q

Origin of supinator m.

A

Deep part = ulna

Superficial part = lateral condyle

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26
Q

Insertion of supinator m.

A

Radial tubercle; oblique line of radius

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27
Q

Action of supinator

A

Supinates forearm

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28
Q

Origin of extensor indices m.

A

Posterior surface of distal ulna

29
Q

Insertion of extensor indices m.

A

Extensor expansion of 2nd digit

30
Q

Action of extensor indices m.

A

Extends 2nd digit; assists extending hand at wrist

31
Q

Origin of abductor pollicis longus m.

A

Posterior half of ulna, radius, and interosseous membrane

32
Q

Insertion of abductor pollicis longus m.

A

Base of 1st metacarpal

33
Q

Action of abductor pollicis longus m.

A

Abduct thumb and extend at carpometacarpal joint

34
Q

Origin of extensor pollicis longus m.

A

Posterior middle-third ulna and interosseous membrane

35
Q

Insertion of extensor pollicis longus m.

A

Dorsal base of distal phalanx of thumb

36
Q

Action of extensor pollicis longus m.

A

Extends distal phalanx of thumb at IPJ; extends at MPJ and carpometacarpal joints

37
Q

Origin of extensor pollicis brevis m.

A

Posterior distal radius and interosseous membrane

38
Q

Insertion of extensor pollicis brevis m.

A

Dorsal base of proximal phalanx of thumb

39
Q

Action of extensor pollicis brevis m.

A

Extends proximal phalanx of thumb at MPJ; extends carpometacarpal joint

40
Q

What is the extensor expansion/extensor hood mechanism as it applies to the hand?

What other muscles participate in this movement?

A

As extensor digitorum contracts, it pulls on the extensor expansion (extensor hood), which causes IP joints to extend

The lumbricals also attach to the expansion at the “hood” and are thus also able to extend the IP joints

41
Q

What provides the arterial supply to the posterior forearm and hand?

A

Posterior interosseous a. (branch of common interosseous a.)

Perforating (posterior) branch of anterior interosseous a.

Radial a. via deep palmar arch and dorsal carpal arch

42
Q

The forearm branches of the radial n. that innervate the posterior forearm include:

The superficial branch of the radial n. which is lateral and runs beneath the ___________ m.

The deep branch of the radial n. which is posterior and becomes the ___________ ___________ n.

A

Brachioradialis

Posterior interosseous

43
Q

The deep branch of the radial n. changes names to the posterior interosseous n. after penetrating what muscle?

A

Supinator m.

44
Q

An injury to the radial n. at the proximal humerus due to humeral fracture or turniquet injury might result in what motion deficits?

A

No elbow extension

Weak supination

45
Q

A radial n. injury at the mid-humeral level results in varying muscle weakness depending on location, usually this is due to a fracture in what part of the bone?

A

Radial groove

46
Q

An injury to the radial n. at the distal humerus due to repetitive forearm rotation, tennis elbow, and/or compression might result in what motion deficits?

A

Wrist drop - inability to extend the hand, metacarpal phalangeal joint, and to fully extend forearm

47
Q

An injury to the radial n. at the wrist such as with trauma, cast, or wristband might result in what primary symptom?

A

Loss of sensation to dorsal hand

[won’t lose any motor component at this level]

48
Q

The radial n. can be injured if a person sustains a fracture to the humeral shaft due to its relationship to the _______ groove.

A

Spiral

49
Q

Describe wrist-drop

A

Paralysis of EXTENSORS of the wrist and fingers –> the flexors take over

Wrist assumes partially flexed position while in a relaxed posture

50
Q

What is the technical term for tennis elbow?

A

Lateral epicondylitis

51
Q

Lateral epicondylitis usually arises as an overuse injury of ___________ muscles from the lateral epicondyle resulting in swelling, tenderness, and pain on wrist extension

A

Extensor

52
Q

What are the 2 primary muscles affected by lateral epicondylitis?

A

Extensor carpi radialis brevis m.

Extensor digitorum m.

53
Q

How is muscle and nerve testing done for the radial n.?

A

Resistance to extension by extensor digitorum m.

54
Q

What is the ONLY nerve to extend the MCP joint?

A

Radial n.

55
Q

What makes up the anatomical snuff box? (Floor, roof, contents, walls)

A

Floor = scaphoid bone

Roof = superficial radial n. branches

Contents = radial a.

Muscular walls = Extensor pollicis longus m., extensor pollicis brevis m.

56
Q

What condition is characterized tenosynovitis of first compartment to thumb APL, EPB?

A

DeQuervain’s disease aka Washer Woman Sprain

57
Q

How is the Finkelstein’s test for DeQuervain’s tenosynovitis done?

A

Thumb in closed fist and hand ulnar deviated

+ test = Pain along radius

58
Q

Origin/insertion/action/innervation:

Brachioradialis m.

A

Origin: supra-epicondylar ridge of humerus

Insertion: lateral distal radius, proximal styloid process

Action: weak arm flexion; maximal when mid-pronated

Innervation: superficial branch of radial n.

59
Q

Origin/insertion/innervation/action:

Extensor carpi radialis longus m.

A

Origin: lateral supra-epicondylar ridge of humerus

Insertion: dorsal side of 2nd metacarpal

Innervation: radial n.

Action: extends/abducts hand at wrist

60
Q

Origin/insertion/innervation/action:

Extensor carpi radialis brevis m.

A

Origin: lateral epicondyle of humerus

Insertion: dorsal base of 3rd metacarpal

Innervation: radial n.

Action: extends/abducts hand at wrist

61
Q

Origin/insertion/innervation/action:

Extensor carpi ulnaris m.

A

Origin: lateral epicondyle; posterior ulna via shared aponeurosis

Insertion: dorsal base of 5th metatarsal

Innervation: radial n.

Action: extends and adducts hand at wrist

62
Q

Origin/insertion/innervation/action:

Extensor digitorum m.

A

Origin: lateral epicondyle

Insertion: extensor expansion of medial 4 digits

Innervation: radial n.

Action: extends primarily at MPJ, but also IPJ; some wrist extension

63
Q

Origin/insertion/innervation/action:

Extensor digiti minimi m.

A

Origin: lateral epicondyle

Insertion: extensor expansion of 5th digit

Innervation: radial n.

Action: extends 5th digit at MPJ but also IPJ

64
Q

Origin/insertion/innervation/action:

Supinator m.

A

Origin: deep part on ulna, superficial part on lateral condyle

Insertion: radial tubercle; oblique line of radius

Innervation: radial n.

Action: supinates forearm

65
Q

Origin/insertion/innervation/action:

Extensor indices m.

A

Origin: posterior surface of distal ulna and interosseous membrane

Insertion: extensor expansion of 2nd digit

Innervation: radial n.

Action: extend 2nd digit; assists extending hand at wrist

66
Q

Origin/insertion/innervation/action:

Abductor pollicis longus m.

A

Origin: posterior half of ulna, radius, and interosseous membrane

Insertion: base of 1st metacarpal

Innervation: radial n.

Action: abducts thumb and extends carpometacarpal joint

67
Q

Origin/insertion/innervation/action:

Extensor pollicis longus m.

A

Origin: posterior middle-third ulna and interosseous membrane

Insertion: dorsal base of distal phalanx of thumb

Innervation: radial n.

Action: extends distal phalanx of thumb at IPJ; extends at MPJ and carpometacarpal joints

68
Q

Origin/insertion/innervation/action:

Extensor pollicis brevis m.

A

Origin: posterior distal radius and interosseous membrane

Insertion: dorsal base of proximal phalanx of thumb

Innervation: radial n.

Action: extends proximal phalanx of thumb at MPJ; extends carpometacarpal joint

MSK Exam II (20 decks)

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