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MMB (Meera) > [007] The Axilla And Brachial Plexus > Flashcards

[007] The Axilla And Brachial Plexus Flashcards

1
Q

What is the axilla and why is it important?

A

The axilla is an area of transition, allowing the passage of nerves and blood vessels from the body into the arm - it is the gateway between the trunk and neck and the upper line

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2
Q

What is the structure of the Axilla?

A

It is roughly pyramidal in shape: 4 walls, a floor, an inlet (apex of the pyramid)

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3
Q

What are the boundaries of the axillary inlet formed from?

A

• The anterior margin = clavicle

• The medial margin = superior margin of rib 1

• the posterior margin= superior margin of the scapula lateral to the coracoid process

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4
Q

What 3 components make up the anterior wall of the Axilla?

A

• Pectoralis major and minor muscles
• susclavius muscle
• Clavipeltoral fascia

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5
Q

What 3 components make up the medial wall of the Axilla?

A

• Thoracic wall (ribs, intercostal muscles)
• Serratus anterior muscles
• Long thoracic nerve and intercostobrachial nerve

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6
Q

What is the base of the Axilla?

A

The skin of the armpit

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7
Q

What is the lateral wall of the Axilla made up of?

A

The intertubercular sulcus of the humerus

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8
Q

What are the 3 components of the posterior wall?

A

• Subscapularis
• Latissimus dorsi
• Teres major muscle
• Long head of the triceps

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9
Q

What are the 4 apertures in the Axilla?

A
  1. Suprascapular foremen
  2. Quandrangular space
  3. Triangular space
  4. Triangular interval
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10
Q

What 2 components make up the suprascapular foramen?

A

The suprascapular nerve and the superior transverse scapular ligament

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11
Q

Which 2 muscles are innervated by the subscapular nerve?

A

The supraspinatus and infraspinatus muscles

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12
Q

Which 2 components pass through the greater scapular notch (spinoglenoid notch)?

A

The subscapular nerve and artery

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13
Q

Which 4 components make up the quandrangular space?

A

• Superiorly: interior margin of the teres minor muscle
• Laterally: surgical neck of the humerus
• Medially: lateral margin of the long head of the triceps
• Inferiorly: superior margin of the teres major muscle

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14
Q

Which 2 structures pass through the quandrangular space?

A
  1. The axillary nerve which innvervates the deltoid and teres minor
  2. The posterior humeral circumflex artery
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15
Q

Why are the axillary nerve and posterior humeral circumflex artery at risk if the humerus is fractured?

A

As both of these structures go through the quadrangular space and run tightly around the back of the surgical neck of the humerus

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16
Q

What structure passes through the triangular space?

A

The circumflex scapular artery

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17
Q

Where is the triangular space?

A

Medial to the quadrangular space

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18
Q

Which 2 structures pass through the triangular interval?

A

• The radial nerve
• The profunda brachii artery

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19
Q

What is a risk for the structures that pass through the space created by these muscles?

A

Sometimes, if these muscles become inflamed and undergo hypertrophy they may compress the nerves/arteries that pass through the space and impact their functioning

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20
Q

What are the 2 muscles within the Axilla?

A
  1. Coracobrachialis
  2. Biceps brachii
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21
Q

What is the origin of the coracobrachialis?

A

The coracoid process of the scapula

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22
Q

What is the insertion of the coracobrachialis?

A

The medial side of the humerus

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23
Q

Which nerves innervate the coracobrachialis?

A

C5 - C6 (musculocutaneous nerves)

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24
Q

What is the origin of the short head of the biceps brachii?

A

The coracoid process

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25
Q

What is the origin of the long head of the biceps brachii?

A

The supraglenoid tubercle

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26
Q

What is the insertion of the biceps brachii?

A

The 2 heads combine to insert onto the radial tuberosity of the forearm

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27
Q

Which nerves innervate the biceps brachii?

A

C5 - C6 (musculocutaneous nerves)

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28
Q

What are the 3 parts of the subclavian artery that supplies the arm?

A

The SUBCLAVIAN ARTERY passes over the 1st rib and changes into the AXILLARY ARTERY. The axillary artery passes out of the Axilla and past the lower boundary of latissimus dorsi and teres major it changes to the BRACHIAL ARTERY.

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29
Q

What are the borders to the 3 parts of the axillary artery?

A

1st part: between the first rib and the pectoralis minor
2nd part: deep to the pectoralis minor
3rd part: between the pectorals minor and the lower boundary of teres major

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30
Q

How many branches come off each part of the axillary artery?

A

1st part: one branch
2nd part: two branches
3rd part: three branches

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31
Q

What is the branch that comes eff the first part of the axillary artery and what does it supply?

A

The superior thoracic artery which supplies the upper medial and anterior axillary walls

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32
Q

What are the two arteries that branch off the second part of the axillary artery?

A

The thoracoacromial artery and the lateral thoracic artery

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33
Q

What does the thoracoacromial artery branch into and what does it supply?

A

Clavicular
Acromial
Deltoid
Pectoral

Cadavers Are Dead People

It supplies blood to the anterior wall of the axilla and chest

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34
Q

What does the lateral thoracic artery supply?

A

The lateral side of the thorax, pectoralis minor and the serratus anterior and medial axillary walls

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35
Q

What are the three branches that come off the third branch of the axillary artery?

A
  1. The subscapular artery
  2. The anterior humeral circumflex artery
  3. The posterior humeral circumflex artery
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36
Q

What does the subscapular artery branch into?

A
  1. The circumflex scapular artery - passes through the triangular space
  2. The thoracodorsal artery
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37
Q

What are the paths of the anterior and posterior humeral circumflex arteries?

A

The anterior humeral circumflex artery goes around the front of the surgical neck of the humerus.

The posterior humeral circumflex artery goes around the back of the surgical neck (through the quadrangular space)

Both these arteries anastomose to form a loop around the surgical neck of the humerus - dangerous in case of a humeral fracture at the surgical neck

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38
Q

What is the pathway from the subclavian to the axillary artery?

A

Subclavian > thyrocervical trunk > suprascapular artery > circumflex scapular > subscapular artery > axillary artery

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39
Q

What is a pathway from the subclavian artery to the axillary artery?

A

Subclavian > transverse cervical artery > deep branch of transverse cervical artery /dorsal scapular > circumflex scapular artery > subscapular artery > axillary artery

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40
Q

Label the numbers in the diagram.

A
  1. Superior thoracic artery
  2. Thoraco-acromial artery
  3. Subscapular artery
  4. Anterior humeral circumflex artery
  5. Posterior humeral circumflex artery
  6. Circumflex scapular artery
  7. Thoracodorsal artery
  8. Lateral thoracic artery
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41
Q

Within the arm and forearm the vein is known as (1) vein, when it crosses the (2) muscle, it becomes the (3) vein, then finally when it crosses the lateral border of the (4) it becomes the (5) vein.

A
  1. Basilic
  2. Teres major
  3. Axillary
  4. Rib 1
  5. Subclavian
42
Q

Within the arm and forearm, the vein is known as the (1) vein, when it crosses the (2) muscle it becomes the (3) vein, then finally when it crosses the lateral border of the (4) it becomes the (5) vein.

A
  1. Basilic
  2. Teres major
  3. Axillary
  4. First rib
  5. Subclavian
43
Q

What lymph nodes are responsible for draining the upper limb and adjacent areas?

A

The axillary lymph nodes

44
Q

What are the 5 groups of axillary lymphatics?

A
  1. Pectoral
  2. Lateral (humerus)
  3. Apical
  4. Central
  5. Subscapular
45
Q

Which rein rums superiorly under the surface of the hard to drain the lateral and posterior parts of the hand?

A

Cephalic vein

46
Q

Which node receives most of the lymphatic drainage of the arms?

A

The humeral node

47
Q

Where does the axillary vein run compared to the axillary artery?

A

The vein is anteriomedial to the artery

48
Q

Where does the cephalic vein run and where does it drain into?

A

Between the deltoid and pectoralis major in the deltopectoral groove
It drains into the axillary vein and drains the upper limb superficially

49
Q

Why are the axillary lymph nodes important in breast cancer?

A

As they are responsible for 75% of the breast drainage and the axillary process of the axilla may enter the axilla

50
Q

What is a plexus?

A

A way to connect the innervation of nerves of different spinal levels into one peripheral nerve

51
Q

Which spinal levels contribute to the brachial plexus?

A

The ventral rami of spinal levels C5 - T1

52
Q

What type of plexus is the brachial plexus and what kind of innervation does it provide to the upper limb?

A

It is a somatic plexus and provides sensory and motor innervation to the upper limb

53
Q

What two areas are not innervated by the brachial plexus?

A

The trapezius and the regiments badge area

54
Q

What innervates the regiments badge area?

A

The intercostobrachial nerve

55
Q

What nerve innervates the trapezius?

A

Cranial nerve (XI)

56
Q

What does the brachial plexus also carry?

A

Sympathetic fibres to the blood vessels, sweat glands and erector pili
Carries grey rami T2-T6

57
Q

What type of innervation is not present in the upper limb?

A

Parasympathetic

58
Q

Where do the roots and trunks of the brachial plexus lie?

A

Between the anterior and middle scalene muscles and inferior to the subclavian artery

59
Q

What is the order of the veins, arteries and brachial plexus at the neck?

A

Vein, artery, brachial plexus (VAP)

60
Q

What are the branches of the C5 root?

A

The dorsal scapular nerve (only C5), long thoracic nerve and a contribution to the phrenic nerve

61
Q

What are the branches of the roots C6-C7?

A

Long thoracic nerve

62
Q

What does the dorsal scapular nerve innervate?

A

The rhomboid muscle and part of the levator scapulae

63
Q

What does the long thoracic nerve innervate?

A

The serratus anterior

64
Q

What clinical sign will patients with a damaged long thoracic nerve present with?

A

A winged scapula

65
Q

Which roots is the superior trunk of the brachial plexus a combination of?

66
Q

Which root is the middle trunk of the brachial plexus a combination of?

67
Q

Which roots is the inferior trunk of the brachial plexus a combination of?

68
Q

What are the two branches coming off the superior trunk?

A

The suprascapular nerve and the nerve to the subclavius

69
Q

What does the suprascapular nerve innervate?

A

The supraspinatus and the infraspinatus muscle
After travelling through the suprascapular foramen

70
Q

What do the anterior divisions of the superior and middle trunk combine to form?

A

The lateral cord

71
Q

What do the posterior divisions of the superior, middle and inferior trunk combine to form?

A

The posterior cord

72
Q

What does the anterior division of the inferior trunk form?

A

The medial cord

73
Q

What are the branches of the lateral cord?

A
  1. Musculocutaneous nerve
  2. Lateral pectoral nerve
  3. Median nerve
74
Q

What are the branches of the posterior cord?

A
  1. Axillary nerve
  2. Radial nerve
  3. Inferior subscapular nerve
  4. Thoracodorsal nerve
  5. Superior subscapular nerve
75
Q

What are the branches of the medial cord?

A
  1. Medial pectoral nerve
  2. Medial cutaneous nerve of the arm
  3. Medial cutaneous nerve of the forearm
  4. Median nerve
  5. Ulnar nerve
76
Q

What are the 4 terminal nerves?

A
  1. Musculocutaneous nerve
  2. Median nerve
  3. Radial nerve
  4. Ulnar nerve
77
Q

What does the lateral pectoral nerve (coming off the lateral cord) innervate?

A

Pectoralis major

78
Q

What does the musculocutaneous nerve (terminal nerve of the lateral cord) innervate?

A

All the muscles of the anterior compartment of the arm (coracobrachialis, brachialis, biceps brachii)
Sensory innervation to the forearm

79
Q

What does the lateral root of the median nerve (terminal nerve of the lateral cord) innervate?

A

All the flexor muscles in the anterior compartment of the forearm (except flexor carpi ulnaris and part of flexor digitorum profundus)
Thenar muscles
Lateral lumbricals (digits 3 and 4)
Sensory innervation of the lateral part of palm + digits 5,4,3 + 1/2 of 2

80
Q

What does the medial pectoral nerve (from the medial cord) innervate?

A

Pectoralis major
Pectoralis minor

81
Q

What does the medial cutaneous nerve of the arm (from the medial cord) innervate?

A

The skin over the medial side of the distal part of the arm
The floor of the axilla

82
Q

What does the medial cutaneous nerve of the forearm (medial cord) innervate?

A

The skin over the medial surface from the forearm down to the wrist

83
Q

What does the medial root of the median nerve innervate?

A

Same as lateral root of the median nerve

84
Q

What does the ulnar nerve (terminal nerve of the medial cord) innervate?

A

Flexor carpi ulnaris and the medial half of flexor digitorum profunda
Medial palmar surface (sensory innervation)

85
Q

What does the superior subscapular nerve (branch of the posterior nerve) innervate?

A

Subscapularis

86
Q

What does the thoracodorsal nerve (branch of the posterior nerve) innervate?

A

Latissimus dorsi

87
Q

What does the inferior subscapular nerve (branch of the posterior nerve) innervate?

A

Subscapularis
Teres major

88
Q

What does the axillary nerve (branch of the posterior nerve) innervate?

A

Deltoids
Teres minor
Regiment’s badge

89
Q

What does the radial nerve (branch of the posterior nerve) innervate?

A

All muscles in the posterior compartment of the arm and forearm

90
Q

PLEASE KNOW THIS

91
Q

What is Erb’s Palsy or Waiter’s tip caused by?

A

Traumatic lateral neck bending

92
Q

What trunk is affected?

A

Superior trunk (C5 - C6)

93
Q

What nerves are damages in Erb’s Palsy?

A

Suprascapular nerve
Dorsal scapular nerve
Axillary nerve
Musculocutaneous nerve
Radial nerve

94
Q

What is Klumpke’s Palsy caused by?

A

Hyperabduction of the arm (e.g. grabbing to stop falling)

95
Q

What is a clinical sign of Klumpke’s Palsy?

A

Claw hand presentation

96
Q

Which nerve is damaged in Klumpke’s Palsy?

A

Ulnar nerve (C8-T1)

97
Q

What causes wrist drop/saturday night palsy?

A

Fracture of humerus
Compressed radial nerve
Improper use of clutches

98
Q

What causes the wrist drop?

A

Loss of extensors (triceps, brachioradialis, supinator and extensors of
wrist and fingers)

99
Q

What are the clinical signs of damage to median nerve?

A

Hand of Benediction/Pope’s Blessing or Hand

100
Q

What causes Hand of Benediction/Pope’s Blessing or Hand?

A

Loss of finger and wrist flexors, thenar muscles, and 1st and 2nd
lumbricals

101
Q

What causes deltoid paralysis?

A

Injury to axillary nerve

102
Q

What are the clinical signs of deltoid paralysis?

A

Inability to abduct arm beyond 15 degrees
Flat shoulder (Atrophy of deltoid, rounded contour of shoulder flattens)
Loss of sensation over regimental badge

MMB (Meera) (7 decks)

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