Internal Thoracic Artery
The Internal Thoracic artery arises from the first part of the subclavian. Lateral to the sternum it has a vertical course behind the costal pleura. It gives rise to anterior intercostal arteries. At the sixth intercostal space it divides into the superior epigastric and musculophrenic arteries.
of the aorta establishes collateral circulation between the aortic intercostals
and the internal thoracic intercostals.