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 ==