Intercostal neurovascular bundles

The intercostal nerve and intercostal vessels travel together as intercostal neurovascular bundles in the intercostal spaces. The intercostal neurovascular bundles lie between the innermost and internal intercostal mm. There are 11 pairs of intercostal neurovascular bundles, one on each side of the thoracic cage.

Anteriorly, the intercostal vessels consist of the anterior intercostal artery and vein (from the internal thoracic vessels). Posteriorly, the intercostal vessels consist of the posterior intercostal artery and vein (from the aorta and azygous system). At some point laterally within the intercostal space, the anterior and posterior intercostal arteries anastomose, as do the anterior and posterior intercostal veins.

The main branches of the intercostal neurovascular bundles run in the superior part of each intercostal space, travelling along the inferior border of the upper rib in the costal groove. The smaller, collateral branches of the intercostal neurovascular bundles run in the inferior part of each intercostal space.