Intercostal arteries are located within the intercostal space and consist of two parts:
1. Single large posterior intercostal artery
2. Two small anterior intercostal arteries
The intercostal arteries supply the area between the ribs.
Grey’s Anatomy 20th edition
Posterior Intercostal Arteries:
The superior intercostal artery, which is a branch of the costocervical trunk, originating from the second part of subclavian artery, gives off the branches which form the posterior intercostal arteries of the first two intercostal spaces.
Descending thoracic aorta gives off branches to the remaining lower nine intercostal spaces, which form the posterior intercostal arteries of these lower nine spaces.
Anterior Intercostal Arteries:
Internal thoracic artery, arising from the first part of the subclavian artery, gives off branches which form the anterior intercostal arteries of the first six intercostal spaces.
Branches arising from each of the intercostal arteries supply the following structures:
3. Parietal Pleura
In the female, the branches supplying the superficial structures in the region of the breast, are especially larger.