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Anatomy > Exam #6: Posterior Compartment > Flashcards

Exam #6: Posterior Compartment Flashcards

1
Q

What innervates the posterior compartment?

A

Posterior divisions of the brachial plexus, specifically:

  • Radial nerve
  • Axillary nerve
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2
Q

What does the axillary nerve innervate?

A

Motor=

  • Deltoid
  • Teres minor

Cutaneous= lateral arm

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3
Q

Review the boudaries of the quadrangular space.

A 
Superior= teres minor 
Inferior= teres major 
Medial= long head of the triceps brachii 
Lateral= Surgical neck of the humerus
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4
Q

What are the contents of the quadrangular space?

A
  • Axillary nerve

- Posterior circumflex humeral a.

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5
Q

What does fracture of the surgical neck of the humerus damage?

A

Quadrangular space

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6
Q

A patient presents in your office following trauma to the proximal humerus with atrophy of the deltoid noted on exam. What should you suspect?

A

Axillary nerve injury

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7
Q

What can glenohumeral dislocation cause?

A

Damage to the contents of the quadrangular space

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8
Q

What are the branches of the radial nerve?

A

Superficial branch

Deep branch

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9
Q

What does the superficial branch of the radial nerve provide?

A

Cutaneous innervation to the dorsum of the hand

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10
Q

What does the deep branch of the radial nerve provide?

A

Motor innervation to the forearm

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11
Q

What is the posterior interosseous nerve?

A

Termination of the deep branch of the radial nerve after it innervation of the supinator muscle

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12
Q

What are the muscles of the posterior compartment of the arm?

A

Triceps Brachii

  • Long (all the way to the shoulder)
  • Lateral
  • Medial

Anconeus

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13
Q

What is the function of the muscles of the posterior compartment of the arm?

A

Extension of the elbow

- Long head can extend the shoulder as well

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14
Q

What nerve innervates the posterior compartment of the arm?

A

Radial nerve

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15
Q

What are the two muscles of the posterior compartment of the arm?

A

Triceps Brachii

Anconeus

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16
Q

What is the function of the anconeus?

A

Assists the triceps in extending the elbow & stabilizes the elbow

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17
Q

What is the exception to the functional rule of the muscles in the posterior compartment of the forearm?

A

Brachioradialis–flexor

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18
Q

Where do the muscles of the posterior compartment of the forearm originate?

A

Either the lateral epicondyle of the humerus or posterior surface of the forearm

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19
Q

List the muscles in the superficial group of the posterior compartment of the forearm.

A
  • Brachioradialis
  • Extensor carpi radialis longus
  • Extensor carpi radialis brevis
  • Extensor carpi ulnaris
  • Extensor digitorum
  • Extensor digiti minimi
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20
Q

What is the origin of the brachioradialis?

A

Lateral supracondylar ridge

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21
Q

What is the insertion of the brachioradialis?

A

Styloid process of the radius

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22
Q

What is the innervation of the brachioradialis?

A

Radial n.

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23
Q

What is the function of the brachioradialis?

A

Flexion of the elbow

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24
Q

What is the origin of the extensor carpi radialis longus?

A

Lateral supracondylar ridge

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25
Q

What is the insertion of the extensor carpi radialis longus?

A

Base of MC II

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26
Q

What is the innervation of the extensor carpi radialis longus?

A

Radial n.

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27
Q

What is the function of the extensor carpi radialis longus?

A

Extends & abducts the wrist

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28
Q

What is the origin of the extensor carpi radialis brevis?

A

Lateral epicondyle

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29
Q

What is the insertion of the extensor carpi radialis brevis?

A

Base of MC III

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30
Q

What is the innervation of the extensor carpi radialis brevis?

A

Deep branch of the radial n.

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31
Q

What is the function of the extensor carpi radialis brevis?

A

Extends & abducts the wrist

32
Q

What is the origin of the extensor carpi ulnaris?

A

Lateral epicondyle

33
Q

What is the insertion of the extensor carpi ulnaris?

A

Base of MC V

34
Q

What is the innervation of the extensor carpi ulnaris?

A

Deep branch of radial n.

35
Q

What is the function of the extensor carpi ulnaris?

A

Extends & adducts wrist

36
Q

What is the origin of the extensor digitorum?

A

Lateral epicondyle

37
Q

What is the insertion of the extensor digitorum?

A

Extensor expansion of digits 2-5

38
Q

What is the innervation of the extensor digitorum?

A

Deep branch of the radial n.

39
Q

What is the function of the extensor digitorum?

A

Extends digits 2-5 at all joints

Extends wrist

40
Q

What is the origin of the extensor digiti minimi?

A

Lateral epicondyle

41
Q

What is the insertion of the extensor digiti minimi?

A

Extensor expansion of digit 5

42
Q

What is the innervation of the extensor digiti minimi?

A

Deep branch of radial n.

43
Q

What is the function of the extensor digiti minimi?

A

Extends digits 5 at all joints

Extends & adducts wrist

44
Q

What are the extensor expansions?

A

Connective tissue around the fingers

45
Q

List the muscles of the deep group of the posterior compartment of the forearm.

A

Supinator
Abductor pollicis longus
Extensor pllicius longus
Extensor pollicus brevis

46
Q

What is the origin of the supinator?

A

Lateral epicondyle, olecranon process

47
Q

What is the insertion of the supinator?

A

Proximo-lateal radius

48
Q

What nerve innervates the supinator?

A

Deep branch of the radial n.

49
Q

What is the function of the supinator?

A

Supination of the forearm

50
Q

What is the origin of the abductor pollicus longus?

A

Posterior ulna
Radius
Interosseous membrane

51
Q

What is the insertion of the abductor pollicus longus?

A

Base of MC I

52
Q

What is the innervation of the abductor pollicus longus?

A

Posterior interosseous n.

53
Q

What is the function of the abductor pollicus longus?

A

Abducts the pollex (thumb)

54
Q

What is the origin of the extensor pollicus longus?

A

Posterior ulna

Interosseous membrane

55
Q

What is the insertion of the extensor pollicus longus?

A

Base of the distal phalanx of the pollex

56
Q

What nerve innervates the extensor pollicus longus?

A

Posterior interosseous n.

57
Q

What is the function of the extensor pollicus longus?

A

Extends pollex at all joints

58
Q

What is the origin of the extensor pollicis brevis?

A

Posterior radius

Interosseous membrane

59
Q

What is the insertion of the extensor pollicis brevis?

A

Base of proximal phalanx of pollex

60
Q

What nerve innervates the extensor pollicis brevis?

A

Posterior interosseous n.

61
Q

What is the function of the extensor pollicis brevis?

A

Extends pollex at the MCP joint

62
Q

What is the anatomical snuff box?

A

Medial= tendon of the extensor pollici longus
Lateral=
- Extensor pollicis brevis
- Abductor pollicis longus

**Note that the two extensor tendons are NOT next to each other

63
Q

What are the contents of the anatomical snuff box?

A

Radial a.

Scaphoid bone

64
Q

What is the origin of the extensor indicis?

A

Posterior ulna

Interosseous membrane

65
Q

What is the insertion of the extensor indicis?

A

Extensor expansion of digit 2

66
Q

What nerve innervates the extensor indicis?

A

Posterior interosseus n.

67
Q

What is the function of the extensor indicis?

A

Extends digit 2 at all joints i.e. extends wrist

68
Q

What two muscles are innervated by the radial nerve?

A

Brachioradialis

Extensor carpi radialis longus

69
Q

What five muscles are innervated by the deep branch of the radial nerve?

A 
Extensor carpi radialis brevis 
Extensory carpi ulnaris 
Extensor digitorum
Extensor digiti mini 
Supinator
70
Q

What four muscles are innervated by the posterior interosseous nerve? What is the mnemonic to remember this?

A

“ABLE muscles”

Abductor pollicis longus
extensor pollicis Longus
extensor pollicis Brevis
Extensor indicis

71
Q

Describe the presentation of a radial nerve injury.

A

“Saturday night palsy, honeymoon palsy, crutch palsy”

  • Wrist drop**
  • Weakness of the triceps
  • Inability to extend wrist & fingers
  • Numbness over the dorsum of the hand & posterior forearm
72
Q

What is the triangular interval?

A 
Lateral= lateral head of the triceps 
Medial= long head of the triceps 
Superior= teres major
73
Q

List the contents of the triangular interval.

A

Radial nerve

Profunda brachii a.

74
Q

What is the common mechanism of injury to the triangular interval?

A

Midshaft humeral fractures that leads to wrist drop

75
Q

What is handcuff palsy?

A

Paresthesia or numbness over the dorsum of the hand between MC I & II caused by compression/ injury to the superficial branch of the radial nerve (distal)

Anatomy (35 decks)

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