The internal mammary artery (internal thoracic artery) is an artery of the anterior chest wall. It supplies the skin and muscles of the anterior thoracic cage, the breast, and the superior aspect of the abdominal wall. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Course The internal mammary artery arises from the proximal portion of the subclavian artery. It then travels inferiorly along the inner surface of the anterior chest wall – approximately 2cm lateral to the sternal margin. The vessel descends in a neurovascular plane between the internal intercostal muscles and costal cartilages anteriorly, and the transversus thoracis muscle posteriorly. At the level of the 1st rib, it is crossed anteriorly by the phrenic nerve. Along its course, the internal mammary artery gives rise to several branches: Anterior and posterior intercostal arteries Pericardiophrenic artery Perforating cutaneous branches Once the internal mammary artery reaches the 6th to 7th costal cartilage, it bifurcates into its terminal branches – superior epigastric artery and musculophrenic artery. By TeachMeSeries Ltd (2025) Fig 1Anatomical course of the internal mammary artery. Supply The internal mammary artery contributes to the blood supply of the following structures: Anterior thoracic wall (sternum, ribs, costal cartilage and intercostal muscles) Pectoral muscles, subcutaneous tissue and skin over the anterior chest Breasts Via the pericardiophrenic artery – thymus, phrenic nerves, pericardium and diaphragm By TeachMeSeries Ltd (2025) Fig 2The internal mammary artery contributes to the blood supply of the structures of the anterior chest wall. Print Article Rate This Article