The internal thoracic artery (previously known as internal mammal artery) arises from the subclavian artery near its origin.
It travels downward on the inside of the ribcage, approximately a centimeter from the sides of the sternum, and thus medial to the nipple. It is accompanied by the internal thoracic vein.
It runs deep to the external oblique, but superficial to the vagus nerve
It continues downward until it divides into the superficial intercostal artery and the inferior epigastric artery around the sixth costal cartilage.
After passing the sixth intercostal space, the internal thoracic artery splits into the following two terminal branches: