Anatomy, Thorax, Internal Mammary (Internal Thoracic) Arteries

Excerpt

The internal thoracic artery, aka the internal mammary artery, supplies the breast and the anterior chest wall. The internal thoracic artery travels along the inner surface of the anterior chest wall on both sides. When it reaches the sixth or seventh intercostal cartilage, it divides into two branches: the musculophrenic and the superior epigastric arteries. The internal thoracic artery arises a few centimeters away from the origin of the subclavian artery. The artery then descends along the inner wall of the anterior rib cage. It is located about two to three centimeters on either side of the sternum and is slightly medial to the nipple. It is almost always accompanied by the large internal thoracic veins that also follow the same course. The internal thoracic artery runs under the fascia and deep to the intercostal muscles. In the proximal part, the internal thoracic artery also gives off other vessels which supply the breast, thymus, mediastinum, and sternum. At each intercostal rib, it gives off an anterior and posterior branch. The internal thoracic artery can be seen pulsating in some cases. It continues its downward course until it reaches the seventh intercostal space and then gives off the superior epigastric and musculophrenic arteries. The superior epigastric artery continues inferiorly along the abdominal wall until it travels just below the umbilicus, where it connects with the inferior epigastric artery. The musculophrenic artery follows the costal margin and supplies the diaphragm.