The Axillary Nerve

Question 1

What are the spinal roots of the axillary nerve?

Answer 1

C5-C6

Question 2

What are the motor functions of the axillary nerve?

Answer 2

It innervates teres minor and deltoid muscles

Question 3

What is the superior boundary of the quadrangular space?

Answer 3

Subscapularis and teres minor

Question 4

What is the inferior boundary of the quadrangular space?

Answer 4

Teres major

Question 5

What is the lateral boundary of the quadrangular space?

Answer 5

Surgical neck of the humerus

Question 6

What is the medial boundary of the quadrangular space?

Answer 6

Long head of triceps brachii

Question 7

What passes through the quadrangular space?

Answer 7

The axillary nerve and the posterior circumflex humeral artery.

Question 8

Teres minor is a part of what?

Answer 8

One of the four rotator cuff muscles. They provide stability to the glenohumeral joint

Question 9

Individually, what does teres minor act to do?

Answer 9

It externally rotates the upper limb.

Question 10

Which branch of the Axillary branch is teres minor innervated by?

Answer 10

The posterior terminal branch

Question 11

What is the function of the deltoid muscle?

Answer 11

Perform abduction of the upper limb at the glenohumeral joint.

Question 12

Where is deltoid situated?

Answer 12

The superior aspect of the shoulder.

Question 13

Which branch of the axillary nerve is deltoid innervated by?

Answer 13

The anterior terminal branch

Question 14

Where is the axillary nerve found?

Answer 14

In the axilla region

Question 15

What part of the brachial plexus is the axillary nerve a continuation of?

Answer 15

The posterior cord hence it contains fibres from the C5 and C6 spinal roots

Question 16

What anatomical course does the axillary nerve take?

Answer 16

• The axillary nerve lies posteriorly the axillary artery and anteriorly to subscapularis
• Descends to the inferior border of subscapularis and then exits the axilla posteriorly via the quadrangular space

Question 17

What does axillary nerve divide into and where?

Answer 17

In the posterior scapula region, it divides into:

• Posterior terminal branch which provides motor innervation to teres major and innervates the skin over the inferior part of deltoid
• Anterior terminal Branch which provides motor innervation to the deltoid muscle

Question 18

Which areas of the skin does the axillary nerve provide sensation?

Answer 18

The superior lateral cutaneous nerve (A branch of the axillary nerve) innervates the skin over the lower deltoid (the regimental badge area)