FMA definition : Venous tree, each instance of which is the vena comitans of some subcostal artery
on the left or right side; it joins some ascending lumbar vein to form some azygos
vein on the right or some hemiazygos vein on the left.;
Venous tree, each instance of which is the vena comitans of some subcostal artery
on the left or right side; it joins some ascending lumbar vein to form some azygos
vein on the right or some hemiazygos vein on the left.