Breast blood supply comes from three sources: Branches of the axillary artery supply the lateral part of the breast. These are the superior thoracic, thoracoacromial, lateral thoracic and subscapular arteries. Branches of the internal thoracic artery, supply the medial part of the breast as the medial mammary arteries. Perforating branches of second, third and fourth intercostal arteries contribute to the supply of the entire breast. Breast veins follow the mentioned arteries. They drain into the axillary, internal thoracic and second to fourth intercostal veins.