AXILLA

INTRODUCTION:

    The axilla is a pyramidal space situated between the upper part of the arm and the chest wall. It resembles four-sided pyramids and has the following

1. 

   
   

   An Apex
2. A base
3. Four walls: Anterior, Posterior, medial and lateral. 
   
   

Boundaries:

 1. Apex/Cervicoaxillary Canal:

• It is directed upwards and medially towards the root of the neck
• It is truncated(not pointed) 

                            Anterior: by the posterior surface of the Clavicle

                            Posterior: by the superior border of the scapula and medial aspect of coracoid process

                            Medial: by the outer border of the first rib.

    This oblique passage is called the Cervicoaxillary canal. The axillary artery, axillary vein and the brachial plexus enter the axilla through this canal.

2. Base or Floor:

• Directed downward.
• Formed by skin, superficial & axillary fascia.
• Convex upward in congurence with concavity of axilla.

3. Anterior wall:

It is formed by the following.

• the pectoral major in front
• The clavipectoral fascia
• Pectoralis minor

4. Posterior wall:

It is formed by the following.

• Subscapularis above
• Teres major
• Latissimus dorsi

5. Medial wall:

It is convex laterally and formed by the following.

1. upper 4 ribs with their IC muscles
2. the upper part of serratus anterior muscles

6. Medial wall:

It is formed by the following.

• the upper part of the shaft of the humerus
• coracobrachialis