The internal thoracic artery (ITA), also known as the internal mammary artery, is an artery that supplies the anterior chest wall and the breasts. It is a paired artery, with one running along each side of the sternum, to continue after its bifurcation as the superior epigastric and musculophrenic arteries.
Structure
The internal thoracic artery arises from the anterior surface of the subclavian artery near its origin. It has a width of between 1-2 mm.
It travels downward on the inside of the rib cage, approximately 1 cm from the sides of the sternum,
Branches
- Mediastinal branches
- Thymic branches
- Pericardiacophrenic arterytravels with the phrenic nerve
- Sternal branches
- Perforating branches
- Twelve anterior intercostal branches, two to each of the top six intercostal spaces. In a given space, the upper branch travels laterally along the bottom of the rib until it anastomoses with its corresponding posterior intercostal artery. The lower branch of the space anastomoses with a collateral branch of the posterior intercostal artery.
After passing the sixth intercostal space, the internal thoracic artery splits into the following two terminal branches:
- Musculophrenic arteryroughly follows the costal margin and it again gives branch for 7,8,9 ribs
- Superior epigastric arterycontinues the course of the internal thoracic artery, travelling downward into the abdominal wall and to the content of rectus sheath
Function
The internal thoracic artery supplies the chest wall and the breasts. and other arterial grafts (e.g. radial artery, gastroepiploic artery) when grafted to the left anterior descending coronary artery, generally the most important vessel, clinically, to revascularize.