Axillary a.

The axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb. 

Its origin is at the lateral margin of the first rib, medial to which it is called the subclavian a. After passing the inferior margin of teres major m. it becomes the brachial a. 

The axillary artery is often referred to as having three parts based on its relationship with the pectoralis minor m. The pectoralis minor m. passes superficial to the artery. 

• First part - the part of the axillary artery medial to pectoralis minor 

• Second part - the part of the axillary artery that lies posterior to pectoralis minor 

• Third part - the part of the axillary artery lateral to pectoralis minor 

The axillary a. becomes the brachial a. when it enters the arm (see figure).