A CASE OF LEFT INFERIOR VENA CAVA OCCURRING IN A FEMALE SUBJECT IN WHOM THE LEFT SUPERIOR INTER- COSTAL VEIN JOINED THE VENA AZYGOS MAJOR, AND THE TWELFTH RIBS WERE ABSENT. By REGINALD J. GLADSTONE, M.D., F.R.C.S., F.R.S.E., Lecturer on Embryology, and Senior Demonstrator of Anatomy, Middlesex Hospital Medical School, London. THE specimen of left inferior vena cava which forms the subject of this paper (see figs. 1 and 2) illustrates not only the persistence of the left posterior cardinal vein in place of the right, but also what I find to be a frequent mode of origin of the vena azygos major, namely, by the union of three tributaries: (1) a large right subcostal vein, which is joined by (2) the right ascending lumbar vein, and (3) a communicating branch from the back of the inferior vena cava or one of its tributaries, most commonly the right renal, or one of the lumbar veins. The communicating vein usually ascends under cover of the right crus of the diaphragm, after having either pierced the crus or passed through the aortic opening along with the commencement of the thoracic duct. The communicating vein is often absent, and when present is usually small; in the former cases the vena azygos major arises by the junction of the right ascending lumbar vein, with the right subcostal vein, and does not pass through the aortic opening of the diaphragm. In the specimen under consideration the com- municating branch (fig. 2) was connected below with the termination of a left lumbar trunk, which joined the inferior vena cava at the level of the 4th lumbar vertebra (22nd V.); it ran upward on the vertebral column, behind the left renal vein and inferior vena cava, and then crossed obliquely behind the aorta to the interval between this vessel and the right crus of the diaphragm. It appeared to be a persistent portion of one, or perhaps a part of both the left and right cardinal veins. It was quite independent of the ascending lumbar veins, which passed up one on each side of the vertebral column behind the psoas muscle. These are formed as inter- segmental vessels, joining the lumbar veins at a period considerably later than that at which the two posterior cardinal veins are first developed. The abnormalities which I shall now describe-were discovered during A Case of Left Inferior Vena Cava 221 I FIG. 1.-Right ascending lumbar vein. 222 Dr Reginald J. Gladstone the dissection of a female subject in the Anatomical Department of the Middlesex Hospital Medical School. THE INFERIOR VENA CAVA. The right and left common iliac veins joined to form the vena cava on the left side of the 5th lumbar vertebra (23rd V.). The right common iliac vein gave off opposite the 6th lumbar vertebra an ascending trunk, which received the right ilio-lumbar vein, and was continuous with an enlarged right ascending lumbar vein, which coursed upward in front of the transverse processes of the lumbar vertebrae, and behind the psoas magnus muscle. A similar ascending lumbar vein was present on the left side, and sprang from the left common iliac vein, at the junction of the ilio-lumbar vein, and at the level of the lower border of the 6th lumbar vertebra (24th V.). A middle sacral vein joined the right common iliac vein on the 6th lumbar vertebra. The inferior vena cava passed upward on the left side of the aorta as far as the 3rd lumbar vertebra, where it crossed obliquely in front of this vessel, and below the origin of the superior mesenteric artery, to reach its usual situation on the right of the aorta. It received the following tributaries:- (1) A communicating branch from the left ascending lumbar vein, opposite the 4th lumbar vertebra. It was from this vein that the com- municating vessel, previously described as forming one of the three vessels which join to form the origin of the vena azygos major, was derived. (2) The left renal vein, which joined opposite the disc between the 3rd and 4th lumbar vertebrae. (3) The left suprarenal vein. (4) The right ovarian vein. (5) A communicating branch from the right ascending lumbar vein, which joined opposite the disc between the 2nd and 3rd lumbar vertebrae. (6) The right renal vein. (7) The right suprarenal vein. (8) The hepatic veins. The left renal vein joined the inferior vena cava considerably lower than the right, the left kidney being nearly an inch and a half below the level of the right. The left renal vein received the left ovarian vein near its junction with the inferior vena cava. The termination of the left suprarenal vein in the inferior vena cava instead of in the left renal vein was probably partly A Case of Left Inferior Veina Cava 223 Dep cervicaltvein. - - - -- B. superior intercostal vein. - - - - - - - . superior intercostal vein. IUpper small asygos vein. 7. Great asygo vein. - - - -- Lower mail Sayg vein. M.D.-- I.i Suboostal vein. _- - _- ---19 Vert. *- ,, I.L.---1 - - - - - - Communicating vein. B..ascending lumbar vein. renal vein. ovarian vein. - - - - - - --L. suprarenal. vein. nIL.-- - -L renal vein. -L. ovarian vein. L L. sending lumbar vein. R. illo-lumbar vein. &L-24 vert. Middle sacral vein. - > ~~~L.illo-lumbar vein. A4 FIG. 2. 224 Dr Reginald J. Gladstone due to the abnormal situation of the vena cava, and partly to the low position of the kidney. The ilio-lumbar vein on the right side terminated in the commencement of the ascending lumbar vein close to its junction with the right common iliac vein; on the left side it ended in the left common iliac vein at the origin of the ascending lumbar vein. THE VENA AzYGOS MAJOR. This vessel was formed on the 11th dorsal vertebra (18th V.), in the manner previously mentioned, by the union of a large subcostal vein with the right ascending lumbar vein, and a communicating vessel from the anastomosing vein between the left ascending lumbar vein and the inferior vena cava. In addition to the usual visceral tributaries, it received veins from all the right intercostal spaces, those draining from the 4th and 5th spaces joining to form a common trunk, and the 1st, 2nd, and 3rd intercostal veins joining to form the right superior intercostal vein. On the left side the vena azygos major received anastomosing branches from the left hemiazygos veins opposite the bodies of the 9th, 8th, 6th, and 5th vertebrae. It also received the left superior intercostal vein, which drained from the 1st, 2nd, and 3rd spaces, and then crossed obliquely over the body of the 4th dorsal vertebra, to join the vena azygos major close to the termina- tion of the right superior intercostal vein. The vein which is represented in fig. 2, joining the superior vena cava near its origin, was the right deep cervical vein (vena profunda cervicis). VENA AZYGOS MINOR INFERIOR. This vessel was formed by the junction of the left ascending lumbar vein with the left subcostal vein. It received tributaries from the lower four intercostal spaces. THE VERTEBRAL COLUMN AND LUMBAR PLEXUS OF NERVES. There were 24 presacral vertebrae, which were related to the cervical, thoracic, and lumbar regions in the following manner: Cervical, 7. Thoracic, 11. Lumbar, 6. The relation which the lumbar nerves had to the spinal column is shown in fig. 3, and it will be observed that the absence of the twelfth ribs was unaccompanied by any marked change in the composition of the lumbar plexus, which conformed closely with the general type. The " nervus A Case of Left Inferior Vena Cava 225 furcalis," namely, the spinal nerve which is divided between the lumbar and sacral plexuses, was the 24th nerve on each side, as is the case in the normal plexus. The upper lumbar nerves, however, showed a tendency towards the " prefixed" type of plexus. The 20th spinal nerve, indicated by the letters I H in fig. 3, probably represented the normal last dorsal or 12th thoracic. It was the only nerve which sent a branch over the iliac crest. Only one branch, however, passed outward on the quadratus lumborum muscle from the 21st spinal nerve, namely, the ilio-inguinal, and thus, although the 19th spinal nerve, the subcostal, had no iliac branch, I have regarded the 20th nerve as the ilio-hypogastric. ORIGIN OF SPINAL NERVES WITH RELATION TO THE VERTEBRAL COLUMN. Right side. Left side. Th. Lumbar. Th. Lumbar. V' 11 1 2 3 4 5 6 1" 11 1 2 3 4 5 6 V2 18 19 120 21 22 23 24 V2 18 19 20 21 22 23 24 SC 19 ... Ea... ...SC. 19 IH .. 20 ...... .. ..... IH .. I I .. .. 21... ..... ..I.2 GO . 21 ... .. ..... GO 21 ... .. .. .. EC .. 21 22... ..... EC.....(21) (22) AO .. .. 21 22... .. ..AO .. .. .. .. AC ... ... * 22 23 24 ... AC ... ... ... 22 2:3 24 0. ... ... 22 23 24 ... 0 . ... 22 23 ... LS ...... .. .. .. 24 255 LS ... ...24 2 SN 19 20 21 22 23 24 25 SN 19 20 21 22 23 24 25 nf. I nf. V1, in the upper line represents the corresponding vertebra of each spinal nerve (S N) figured below, arranged according to the different regions of the spinal column. V2, in the second line represents the number of each vertebra enumerated from the atlas, to the last lumbar vertebra. S N, in the lowest line the number of the spinal nerve, and nf. in the same line the " nervous furcalis. " S C. Sub postal nerve. E C. External cutaneous nerve. I H. Ilio-hypogastric nerve. A O.