Intercostal vessels and nerve runs in:

(Between the innermost intercostal and internal intercostal muscle) (208-BDC-l 4th) (57-Snell 7th)* Each intercostal space contains a large single posterior intercostal artery and two small anterior intercostal arteries.* The corresponding posterior intercostal vein drain backward into the azygos or hemiazygos vein and the anterior intercostal vein drain forward into the internal thoracic and musculophrenic veinsIntercostal nerves* The intercostal nerves are the anterior rami of the first 11 thoracic spinal nerves. The anterior ramus of the 12th thoracic nerve lies in the abdomen and runs forward in the abdominal wall as the subcostal nerve* In the costal groove the nerve lies below the posterior intercostal vessels. The relationship of structures in the costal groove from above downwards is vein-artery-nerve (VAN)*** Each intercostal nerve enters an intercostal space between the parietal pleura and the posterior intercostal membrane. It then runs forward inferiorly to the intercostal vessels in the subcostal groove of the corresponding rib, between the innermost intercostal and internal intercostal muscle