The Axilla

The axilla is actually a fascial space

it is filled with loose structures (vessels, nerves, lymph nodes, etc.)

it also contains dense structures (muscle, bone)

Axillary Borders

Posterior wall

primarily the subscapularis muscle (scapula)

teres major muscle

latissimus dorsi muscle

Together the teres major and latissimus dorsi muscles make up the posterior axillary fold

Lateral wall

intertubercular sulcus of the humerus

2 tendons

biceps brachii

coracobrachialis

Anterior wall

Pectoralis major and minor muscles

subclavius muscle (clavicle) and associated clavipectoral fascia

The Pectoralis major forms the anterior axillary fold

Medial wall

Serratus anterior muscle and fascia over the first 4 or 5 ribs

Roof

Does not exist but rather is an opening called the cervicoaxillary canal (or inlet of the axilla) bound anteriorly by the clavicle, posteriorly by the scapula, and medially by the first rib

Apex

formed by the convergence of 3 bones

1) clavicle in the anterior wall

2) scapula in the posterior wall

3) first rib in the medial wall

Base

inferiorly is the outlet of the axilla

fascia and skin of the axilla

Lymphatics of the axilla

There are five groups of axillary nodes

Lateral group -is located along the lateral wall of the axilla. Drains the entire upper limb.

Posterior group - (subscapular group) near subscapular artery. Drains the lower part of the back of the neck and posterior aspect of the thoracic wall.

Central group - near the base of the axilla.

Apical group - posterior and superior to the border of the pectoralis minor muscle.

Pectoral group - near the medial wall of the axilla, around the lateral thoracic artery, along the pectoralis minor muscle and may be found between the pectoral muscles. Drains the anterior and lateral thoracic walls and mammary glands.

Axillary Artery

Begins at the lateral boarder of the first rib as a continuation of the subclavian artery

Ends at the inferior boarder of the teres major muscle where it becomes the brachial artery

The axillary artery has three regions:

The region proximal to the pectoralis minor muscle.

This region has 1 branch, the supreme thoracic artery

The region behind the pectoralis minor muscle.

This region has 2 branches:

1. thoracoacromial trunk

2. lateral thoracic artery

The region distal to the pectoralis minor muscle.

This region has 3 branches:

1. subscapular artery

2. anterior circumflex humeral artery

3. posterior circumflex humeral artery

The thoracoacromial trunk has four branches (APCD):

A. acromial

P. pectoral

C. clavicular

D. deltoid

The subscapular artery has two branches:

1. scapular circumflex artery

2. thoracodorsal artery to latissimus dorsi muscle