抄録
A study was carried out in 16 adult cadavers to present the definite features of the lumbar azygos vein, i.e. the lumbar prevertebral longitudinal vein which anastomoses cranially with the azygos system of veins and caudally with the inferior caval system, and has been designated as the left or right lumbar azygos vein, the intermediate root of origin of the azygos (or hemiazygos) vein, and so on.
By the manners of anastomosis with the azygos system, lumbar azygos veins were classified into the following 3 types:
(1) Type I anastomoses with the azygos vein.
(2) Type II anastomoses with the hemiazygos vein.
(3) Type III is slightly Y-shaped and anastomoses with the azygos and hemiazygos veins.
10 specimens had the single lumbar azygos vein. Five of them were of type III, four type I, and one type II. The other 6 specimens had double lumbar azygos veins. Four of them were of type I and II, and two type I and III.
Caudal terminations of all the 22 examples of the lumbar azygos vein were as follows regarding the cranial type:
There were 10 examples of type I, 7 of which anastomosed with the lumbar vein, 2 with the inferior caval vein, and 1 terminated attaching to the lumbar trunk. In 5 examples of type II, 3 anastomosed with the left renal vein, and 2 with the lumbar vein. Then, in 7 examples of type III, 3 anastomosed with the lumbar vein, 2 with the inferior caval vein, and the remaining 2 with the left renal vein and the reno-caval arch, respectively.
The mean diameter of the lumbar azygos veins was 1.7mm.
14 examples out of 22 received the branches of the anterior external plexus.
In their courses, type I passed through the right crus of the diaphragm or the aortic opening, type II and type III passed through the left crus or the aortic opening.
All of the lumbar azygos veins lay dorsomedially to the splanchnic nerve, but their positions relative to the segmental arteries were irregular and sometimes indeterminable.
The present observations and the studies carried out by previous authors, especially by Abe, suggest that the "lumbar azygos vein" is the homologue of the azygos vein system.
