The axillary artery is a large blood vessel that carries oxygenated blood to various parts of the upper body. These parts of the body include the thorax, upper limb, and axilla (more commonly known as the armpit). The thorax of the human body ranges from the neck to the abdomen. The upper limb refers to the arm from the shoulder to the hand. The axillary artery is a continuation of the subclavian artery and begins when it crosses the first rib. As it moves downward it becomes the brachial artery. The axillary artery can be subdivided into three segments. These parts are identified by their location relative to the pectoralis minor muscle, which is located in front of the axillary artery. The first part of the artery is located medial (near the middle) to the pectoralis minor muscle. The second part of the artery is behind the pectoralis minor muscle. The third part of the artery is lateral (to the side of, or farther away from the middle) to the pectoralis minor muscle. The three parts of the axillary artery work together to supply oxygenated blood to the thorax, upper limb, and axillary regions. The axillary vein runs alongside the axillary artery and brings blood back to the heart.