Neurovasculature of intercostal spaces

• Arteries: The posterior intercostal arteries supply blood to the intercostal spaces. The first two spaces are supplied by the supreme intercostal artery (a branch of the costocervical trunk). The remaining nine spaces are supplied by the descending aorta.
• Veins: The intercostal veins drain blood from the intercostal spaces. They generally follow the same pattern as the arteries, with posterior intercostal veins draining into the azygos vein or hemiazygos vein, and the first two draining into the supreme intercostal vein.
• Nerves: The intercostal nerves are the anterior rami of the thoracic spinal nerves (T1-T11). They run within the intercostal spaces, typically located between the internal and innermost intercostal muscles, along with the intercostal arteries and veins. The subcostal nerve (T12) is also considered part of this system.

This neurovascular bundle is crucial for the function of the thoracic wall, including respiration and sensation.