The lateral thoracic artery also goes by the name of the external mammary artery. It distributes oxygenated blood to lateral regions of the breast and upper thorax. Branching off from the axillary artery, the lateral thoracic follows the pectoralis minor muscle’s lower border. At the side of the chest, it services the serratus anterior muscle. The similarly named lateral thoracic vein runs along the same course. While the artery delivers oxygenated blood, the vein drains away the blood once it becomes deoxygenated. From there, the blood flows into the axillary vein, and eventually it ends up back at the lungs and heart. From there, new oxygen is introduced into the blood stream before it is re-circulated. Depending on gender, there is a slight anatomical variation with the lateral thoracic artery and surrounding blood vessels. Females require a slightly different flow and volume of blood within their chests. This relates to the fact that females possess a much more intricate system of body tissue within their breasts and mammary glands. In men, the region of the chest is mostly muscle tissue.