HS1-9 Axilla Flashcards

1
Q

What is the cervico-axillary canal?

A

the passageway connecting the neck and arm for neurovascular structures that enter and leave the arm

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2
Q

What is the apex of the axilla?

A

cervico-axillary canal, which is bounded by the 1st rib, clavicle, and scapula

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3
Q

What is the base of the axilla?

A

axillary fossa (armpit)

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4
Q

What is the anterior wall of the axilla?

A

two layers formed by pectoralis major and minor + anterior axillary fold

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5
Q

What is the posterior wall of the axilla?

A

scapula and subscapularis + posterior axillary fold

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6
Q

What is the medial wall of the axilla?

A

first 4 ribs w/ associated intercostal muscles + overlying serratus anterior

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7
Q

What is the lateral wall of the axilla?

A

intertubercular groove of humerus

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8
Q

In terms of blood supply, which branch of the aorta supplies the arm? How does the name of this structure change?

A

aorta > subclavian artery/vein > becomes axillary artery/vein after crossing 1st rib > becomes brachial artery/basilic vein after crossing teres major

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9
Q

How does the clavicle divide the brachial plexus?

A

into a supraclavicular part and an infraclavicular part

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10
Q

Describe the borders of the deltopectoral (a.k.a. clavipectoral) triangle.

A

clavicle, deltoid, and pectoralis major

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11
Q

Describe the positioning of the cephalic vein in relation to the deltopectoral triangle.

A

runs along anteriolateral aspect of arm and then passes through triangle to drain into axillary vein

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12
Q

Describe the borders of the quadrangular space.

A

long head of triceps brachii + teres major + teres minor + humerus

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13
Q

Describe the borders of the triangular space.

A

teres major + teres minor + long head of triceps brachii

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14
Q

What vascular structure passes through the triangular space?

A

circumflex scapular artery, a branch of the axillary artery

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15
Q

What is the axillary sheath?

A

sleeve of tough fascia that encases the axillary artery/vein + parts of the brachial plexus

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16
Q

What are the three “parts” of the axillary artery?

A

first part above muscle; second part behind muscle; third part below muscle

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17
Q

How many branches (typically) does the axillary artery give off?

A

6

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18
Q

What are the branches of the first part of the axillary artery?

A

superior thoracic artery

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19
Q

What are the branches of the second part of the axillary artery?

A

thoraco-acromial artery; lateral thoracic artery

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20
Q

Describe the location of the thoraco-acromial artery.

A

passes above superior part of pectoralis minor

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21
Q

What does the thoraco-acromial artery supply?

A

anterior shoulder muscles

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22
Q

What does the lateral thoracic artery supply?

A

chest wall

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23
Q

The lateral thoracic artery gives rise to

A

lateral mammary branches

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24
Q

What are the branches of the third part of the axillary artery?

A

subscapular artery (divides into circumflex scapular + thoracodorsal artery) and anterior/posterior circumflex humeral arteries

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25
Q

The circumflex scapular artery supplies

A

lateral border of scapula

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26
Q

The thoracodorsal artery supplies

A

muscles of posterior axillary wall

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27
Q

Describe the location of the anterior circumflex humeral artery.

A

passes laterally around front of surgical neck of humerus

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28
Q

Describe the location of the posterior circumflex humeral artery.

A

passes around posterior aspect of surgical neck of humerus

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29
Q

The posterior circumflex humeral artery supplies

A

deltoid; glenohumeral joint

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30
Q

Why are anastomoses important?

A

because they are connections from one vessel to another, if supply to one vessel is cut off, the other vessel can still function properly

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31
Q

What is the anastomotic network for the scapula?

A

main source: branches of first part of axillary artery; secondary source: third part of axillary artery

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32
Q

What are the branches of the subclavian artery?

A

dorsal scapular artery (first one off); suprascapular artery

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33
Q

The dorsal scapular artery supplies

A

rhomboids; partially, the supra/infrapsinous fossae

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34
Q

The suprascapular artery supplies

A

the supra/infraspinatus within the scapular fossae

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35
Q

Where does the subscapular artery originate?

A

branch of third part of axillary artery

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36
Q

What are the branches of the subscapular artery?

A

circumflex scapular artery; thoracodorsal artery

37
Q

What is the function of the circumflex scapular artery?

A

forms anastomose w/ branches of subclavian artery for scapula

38
Q

What does the thoracodorsal artery supply?

A

subscapularis; teres major

39
Q

The axillary vein is a continuation of

A

the basilic vein

40
Q

Where does the axillary vein begin?

A

lower border of teres major muscle

41
Q

Where do the brachial veins begin?

A

come off the axillary vein near subscapularis muscle

42
Q

The axillary vein has how many parts?

A

3, just like the axillary artery

43
Q

The first part of the axillary vein gives rise to

A

(first part which ends at 1st rib) - becomes subclavian vein

44
Q

Which is more numerous — arteries or veins of the axilla?

A

veins of the axilla

45
Q

The brachial plexus is divided into what 5 parts?

A

roots, trunks, divisions, cords, branches (Real Texans Drink Cold Beer)

46
Q

**Draw out the brachial plexus.

A

*draw out*

47
Q

What are the roots of the brachial plexus?

A

5 nerve roots consisting of anterior primary rami of C5 through T1 spinal nerves

48
Q

What is a prefixed or postfixed brachial plexus?

A

prefixed: when the C4 spinal root contributes significantly
postfixed: when the T2 spinal root contributes significantly

49
Q

What are the trunks of the brachial plexus?

A

superior trunk = C5 + C6 roots; middle trunk = C7 root; inferior trunk = C8 + T1 roots

50
Q

What are the divisions of the brachial plexus?

A

trunks divide to form 3 anterior and 3 posterior divisions

51
Q

What are the cords of the brachial plexus?

A

lateral cord = anterior division of superior + middle trunks; medial cord = anterior division of inferior trunk; posterior cord = posterior division of superior + middle + inferior trunk

52
Q

What nerves come off the roots of the brachial plexus?

A

dorsal scapular nerve (rhomboids, levator scapulae); long thoracic nerve (serratus anterior)

53
Q

What nerves come off the trunks of the brachial plexus?

A

superior trunk - suprascapular nerve (supraspinatus, infraspinatus); subclavian nerve

54
Q

What nerves come off the divisions of the brachial plexus?

A

none

55
Q

What nerves come off the medial cord of the brachial plexus?

A

medial pectoral nerve (pectoralis minor + major); medial cutaneous nerve of arm (skin of anterior arm); medial cutaneous nerve of forearm (skin of anterior forearm); medial root of median nerve (forearm flexor muscles); ulnar nerve (hand muscles)

56
Q

What nerves come off the lateral cord of the brachial plexus?

A

lateral pectoral nerve (pectoralis major); lateral root of median nerve; musculocutaneous nerve (muscles of anterior arm and skin of lateral forearm)

57
Q

What nerves come off the posterior cord of the brachial plexus?

A

upper subscapular nerve (subscapularis); lower subscapular nerve (subscapularis, teres major); thoracodorsal nerve (latissimus dorsi); radial nerve (posterior compartment muscles and skin of arm/forearm); axillary nerve (deltoid, teres minor, skin of shoulder) - ULTRA

58
Q

**Label the following diagram showing cutaneous innervation of the upper limb.

A

insert image here

59
Q

**Label the following diagram showing segmented cutaneous innervation of the upper limb.

A

insert image here

60
Q

**Identify which spinal segments contribute to the following movements.

A

abduction/adduction/extension/flexion at glenohumeral joint

61
Q

**Identify which spinal segments contribute to the following movements.

A

extension/flexion at elbow joint

62
Q

**Identify which spinal segments contribute to the following movements.

A

pronation/supination at proximal and distal radio-ulnar joints

63
Q

**Identify which spinal segments contribute to the following movements.

A

flexion/extension at radiocarpal (wrist) joint

64
Q

Upper brachial plexus injuries involve which spinal segments?

A

C5 and C6

65
Q

How do upper brachial plexus injuries typically occur?

A

when shoulder and neck are violently separated

66
Q

The violent separation of the shoulder and neck can result in what clinical presentation?

A

paralysis of muscles in shoulder and arm (Erb-Duchenne palsy), resulting in “waiter’s tip” posture

67
Q

What is the anatomical basis behind the waiter’s tip posture?

A

With a C5-C6 injury, C6-C8 nerves are mostly spared, and these nerves are responsible for adduction and medial rotation, so the limb hangs by the side of the body (adducted) in medial rotation unopposed by antagonistic muscles that rely on C5-C6 for abduction and lateral rotation

68
Q

**Label the following diagram.

A

axillary nerve course

69
Q

How do lower brachial plexus injuries typically occur?

A

when the upper limb is suddenly pulled superiorly, injuring the inferior trunk of the brachial plexus

70
Q

What are the clinical manifestations of lower brachial plexus injuries?

A

claw-hand posture because the intrinsic muscles of the hand (supplied by T1) are affected

71
Q

What spinal segments are typically associated with lower brachial plexus injuries?

A

C8 and T1

72
Q

What two brachial plexus branches are particularly susceptible to damage due to their exposure?

A

long thoracic nerve; axillary nerve

73
Q

What is a clinical manifestation of damage to the long thoracic nerve?

A

winged scapula, because the medial border of the scapula moves posteriorly and laterally upon immobilization of the serratus anterior

74
Q

Winged scapula is a result of damage to what structure?

A

long thoracic nerve

75
Q

What are the clinical manifestations of damage to the axillary nerve?

A

weakness of abduction and lateral rotation of arm at glenohumeral joint; loss of sensation on lateral side of shoulder

76
Q

**Label the following diagram of axillary artery derivatives.

A

axillary artery derivatives - Sixties Teens Love Sex And Pot

77
Q

**Label the following diagram of collateral circulation. Show how you can preserve blood flow even if you cut off circulation via the subclavian or axillary artery.

A

collateral circulation — preserve blood flow via transverse cervical artery

78
Q

**Label the following diagram of upper limb veins.

A

upper limb veins

79
Q

The subscapular artery bifurcates into

A

thoracodorsal + circumflex scapular artery

Sex (subscapular) gives you S(circumflex scapular) TD(thoracodorsal)s

80
Q

How do you tell the difference between the cutaneous nerve to the forearm and the cutaneous nerve to the arm?

A

cutaneous nerve to the forearm is a lot longer

81
Q

Outline the path of the musculocutaneous nerve.

A

from lateral cord > pierces coracobrachialis > travels under biceps brachii > innervates (motor branches) coracobrachialis, biceps brachii, and brachialis > emerges laterally from biceps brachii and becomes lateral cutaneous nerve of forearm (no longer motor neuron)

82
Q

Outline the path of the axillary nerve.

A

from posterior cord > travels back through quadrangular space > innervates (motor function) deltoid and teres minor + (sensory function) shoulder skin

83
Q

Outline the path of the radial nerve.

A

from posterior cord > travels along radial groove of humerus > seen in triangular interval > innervates (motor function) triceps brachii > sends motor branches to brachioradialis + extensor carpi radialis longus, then splits > superficial branch sends sensory fibers to dorsolateral hand but deep branch sends motor fibers to extensor carpi radialis brevis + supinator > enters posterior forearm as posterior interosseous nerve

84
Q

What does the mnemonic “2, 2, and the Rest” for the radial nerve refer to?

A

2 - sends motor branches to brachioradialis + extensor carpi radialis longus, then splits

2 - deep branch sends motor fibers to extensor carpi radialis brevis + supinator

Rest - as the posterior interosseus nerve, innervates everything in the posterior compartment

85
Q

Outline the path of the ulnar nerve.

A

from medial cord > travels behind medial epicondyle > muscular branch innervates (motor) flexor carpi ulnaris + ulnar half of flexor digitorum profundus > deep branch innervates (motor) all intrinsic hand muscles except lateral lumbricals and thenar muscles > sensory branches give sensory fibers to ulnar portion of hand

86
Q

Outline the path of the median nerve.

A

from medial + lateral cords > gives off anterior interosseus nerve in forearm, which innervates all of deep layer flexor compartment except ulnar half > median nerve continues and gives motor fibers to rest of flexor compartment > travels through carpal tunnel > median nerve innervates (motor) lateral lumbricals > median nerve recurrent branch gives motor fibers to thenar muscles > median nerve gives cutaneous innervation to lateral dorsal hand

87
Q

**Identify which nerves are responsible for innervation of the shaded regions.

A
88
Q

Klumpke paralysis is associated with what clinical presentation and what injury?

A

claw hand posture - lower brachial plexus injury

89
Q

What is thoracic outlet syndrome?

A

compression of neurovascular structures passing through cervico-axillary canal (a.k.a. thoracic outlet) that can cause pain, numbness, tingling etc.