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Flashcards in Axillary Nerve Deck (39)
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1
Q

What is the axillary nerve?

A

A major peripheral nerve of the upper limb

2
Q

What are the spinal roots of the axillary nerve?

A

C5 and C6

3
Q

What does the axillary nerve give rise to?

A

The superior lateral cutaneous nerve of the arm

4
Q

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

A

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

5
Q

What muscles does the axillary nerve innervate?

A

Teres minor
Deltoid muscle
Abductors of the arm at the shoulder

6
Q

Where is the axillary nerve formed?

A

Within the axilla region

7
Q

What is the axillary nerve formed from?

A

Direct continuation of the posterior cord of the brachial plexus

8
Q

What nerve fibres does the axillary nerve contain?

A

Those from the C5 and C6 nerve roots

9
Q

Where does the axillary nerve lie immediately after its formation?

A

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

10
Q

What course does the axillary nerve take?

A

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

11
Q

What is the axillary nerve accompanied by?

A

The posterior circumflex humeral artery

12
Q

Where does the axillary nerve terminate?

A

In the posterior scapular region

13
Q

How does the axillary nerve terminate?

A

By dividing into two branches

14
Q

What two branches does the axillary nerve divide into?

A

Posterior terminal branch

Anterior terminal branch

15
Q

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

A

Motor innervation to teres minor muscle

Innervates skin over inferior part of deltoid

16
Q

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

A

Motor innervation to the deltoid muscle

17
Q

What is the quadrangular space?

A

A gap in the muscles of the posterior scapula region

18
Q

What is the purpose of the quadrangular space?

A

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

19
Q

What is the superior boundary of the quadrangular space?

A

Subscapularis and teres minor

20
Q

What is the inferior boundary of the quadrangular space?

A

Teres major

21
Q

What is the lateral boundary of the quadrangular space?

A

Surgical neck of humerus

22
Q

What is the medial border of the quadrangular space?

A

Long head of the triceps brachii

23
Q

What passes through the quadrangular space?

A

The axillary nerve and posterior circumflex humeral artery

24
Q

What muscles does the axillary nerve innervate?

A

Teres minor

Deltoid muscles

25
Q

What is the teres minor part of?

A

The rotator cuff muscles 1

26
Q

What do the rotator cuff muscles do?

A

Acts to stabilise the glenohumeral joint

27
Q

What does the teres minor do acting individually?

A

Externally rotates the upper limb

28
Q

What is the teres minor innervated by?

A

The posterior terminal branch of the axillary nerve

29
Q

Where is the deltoid situated?

A

At the superior aspect of the shoulder

30
Q

What does the deltoid perform?

A

Abduction of the upper limb at the glenohumeral joint

31
Q

What is the deltoid innervated by?

A

The anterior terminal branch of the axillary nerve

32
Q

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

A

Its posterior terminal branch

33
Q

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

A

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

34
Q

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

A

The skin over the inferior portion of the deltoid

35
Q

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

A

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
Q

How is the axillary nerve most commonly damaged?

A

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

37
Q

How does injury to the axillary nerve affect motor functions?

A

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

38
Q

How does injury to the axillary nerve affect sensory functions?

A

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

39
Q

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

A

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