Axillary Nerve Flashcards Preview

ESA 2- Musculoskeletal System > Axillary Nerve > Flashcards

Flashcards in Axillary Nerve Deck (39):
1

What is the axillary nerve?

A major peripheral nerve of the upper limb

2

What are the spinal roots of the axillary nerve?

C5 and C6

3

What does the axillary nerve give rise to?

The superior lateral cutaneous nerve of the arm

4

What does the superior lateral cutaneous nerve of the arm do?

Innervates the skin over the lower deltoid (regimental badge area)

5

What muscles does the axillary nerve innervate?

Teres minor 
Deltoid muscle 
Abductors of the arm at the shoulder

6

Where is the axillary nerve formed?

Within the axilla region

7

What is the axillary nerve formed from?

Direct continuation of the posterior cord of the brachial plexus

8

What nerve fibres does the axillary nerve contain?

Those from the C5 and C6 nerve roots

9

Where does the axillary nerve lie immediately after its formation?

Posterior to the axillary artery, and anteriorly to the subscapularis muscle

10

What course does the axillary nerve take?

It descends to the inferior border of the subscapularis muscle, and then exits the axilla posteriorly via the quadrangular space

11

What is the axillary nerve accompanied by?

The posterior circumflex humeral artery

12

Where does the axillary nerve terminate?

In the posterior scapular region

13

How does the axillary nerve terminate?

By dividing into two branches

14

What two branches does the axillary nerve divide into?

Posterior terminal branch
Anterior terminal branch

15

What does the posterior terminal branch of the axillary nerve provide?

Motor innervation to teres minor muscle
Innervates skin over inferior part of deltoid

16

What does the anterior terminal branch of the axillary nerve provide?

Motor innervation to the deltoid muscle

17

What is the quadrangular space?

A gap in the muscles of the posterior scapula region

18

What is the purpose of the quadrangular space?

it is a pathway for neurovascular structures to move from the axilla to the posterior shoulder and arm

19

What is the superior boundary of the quadrangular space?

Subscapularis and teres minor

20

What is the inferior boundary of the quadrangular space?

Teres major

21

What is the lateral boundary of the quadrangular space?

Surgical neck of humerus

22

What is the medial border of the quadrangular space?

Long head of the triceps brachii

23

What passes through the quadrangular space?

The axillary nerve and posterior circumflex humeral artery

24

What muscles does the axillary nerve innervate?

Teres minor 
Deltoid muscles

25

What is the teres minor part of?

The rotator cuff muscles 1

26

What do the rotator cuff muscles do?

Acts to stabilise the glenohumeral joint

27

What does the teres minor do acting individually?

Externally rotates the upper limb

28

What is the teres minor innervated by?

The posterior terminal branch of the axillary nerve

29

Where is the deltoid situated?

At the superior aspect of the shoulder

30

What does the deltoid perform?

Abduction of the upper limb at the glenohumeral joint

31

What is the deltoid innervated by?

The anterior terminal branch of the axillary nerve

32

What is the sensory component of the axillary nerve delivered via?

Its posterior terminal branch

33

What course does the posterior terminal branch take to provide sensory innervation?

After it has innervated the teres minor, it continues as the upper lateral cutaneous nerve of the arm

34

What does the upper lateral cutaneous nerve of the arm innervate?

The skin over the inferior portion of the deltoid

35

What can happen to sensation if the axillary nerve is damaged?

Sensation in the regimental badge area may be impaired or absent 
May also report paraesthesia (pins and needles) in the distribution of the axillary nerve

36

How is the axillary nerve  most commonly damaged?

By trauma to the shoulder or proximal, such as a fracture to the humerus surgical neck

37

How does injury to the axillary nerve affect motor functions?

Causes paralysis of the deltoid and teres minor muscles, which renders the patient unable to abduct the affected limb

38

How does injury to the axillary nerve affect sensory functions?

The upper lateral cutaneous nerve of the arm will be non functional, resulting in loss of sensation over the regimental badge area

39

What are the characteristic clinical signs of an injury to the axillary nerve?

In long standing cases, the paralysed deltoid muscle rapidly atrophies, and the greater tuberosity can be palpated in that area