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Anterior intercostal arteries
Other Terms: Intercostal branch of internal thoracic artery
The anterior intercostal arteries arise from the internal thoracic artery in the upper five or six interspaces and from the musculophrenic artery. In each of the interspaces, one artery passes along the upper border of the rib below and another along the lower border of the rib above. These arise separately from the internal thoracic or the musculophrenic artery. It then divides into the branches described. These branches follow the course of the ribs and anastomose, after piercing the internal intercostal muscle, in the first interspace with the branches of the costocervical trunk, and in the other interspaces with the aortic intercostal arteries. At first these arteries lie between the internal intercostal muscles and the pleura. Then they lie between the external and internal intercostal muscles, which they supply. They also supply the ribs.