Figure 2-3
Blood vessels of the anterior thoracic wall.

Figure 2-4
Blood vessels of the posterior thoracic wall.

The blood supply to the anterior thoracic wall is provided by a pair of internal thoracic arteries arising from the subclavian arteries. These two internal thoracic arteries give rise to the anterior intercostal arteries which lie between each set of ribs. Blood is returned from the anterior thoracic wall by anterior intercostal veins carrying blood to the internal thoracic veins which empty into the right and left brachiocephalic veins. (Figure 2-3)

The blood supply to the posterior thoracic wall is supplied by the descending aorta which gives rise to the posterior intercostal arteries.

The posterior thoracic wall is drained by posterior intercostal veins which empty into a unique azygous (unpaired) venous system. The azygous vein eventually empties into the posterior aspect of the superior vena cava. (Figure 2-4)

Anterior and posterior intercostal arteries and veins anastomose with each other near the lateral edge of the thorax.