Inferior Vena Cava
(pl 257 in 3rd)

Outline
Formed by confluence of R and L common iliac veins over the 5th lumbar vertebra
Ascends retroperitneally to R of aorta, then passes into a groove in liver (occasionally embedded) before perforating tendinous portion of diaphragm and pericardiam to enter inferoposterior R atrium.
No valves

Relationships
Crossed at origin by R common iliac; though more commonly at L common iliac vein
Crossed by root of mesentery, right gonadal from left to right and lies behind duodenal C / pancreas head
Posterior to epiploic foramen, covered only by peritoneum; then runs up to R of caudate lobe
- best accessed here, can be slung at level above renal veins if required.
- if want to isolate renal veins, will need to Kocherize duodenum for retropancreatic caval access.
Right adrenal lies to its right and partly behind the cava as it becomes retrohepatic.
Overlies the sympathetic chain in abdominal course.

Tributaries
1. Lumbar veins
- usually 4 pairs, only 3rd and 4th drain into cava;
- the two left veins pass behind the aorta; at risk when aorta mobilized
- right veins easily damages when doing a sympathectomy
2. Gonadal veins
- on R, drain to IVC just below the renal vein.
- L one drains into the L renal vein
3. Renal veins
- enter at 45 to the vertical and left vein usually higher by 1-2cm
- R renal vein short - 2cm
- L vein is long and intimate to aorta, draping over it, usually just below the SMA origin.
- L renal vein recieves a large left adrenal from above and left gonadal, both entering to left of aorta
4. R supra-renal vein
- is short and drains into the IVC just before it becomes retrohepatic
5. Inferior phrenic vein
- R inferior phrenic drains the underurface of the diaphragm
- drains to IVC just above the entrance of the right hepatic vein
6. Hepatic veins
- several
- lower group are small and variable - from 1 to a few; caudate and often a VIII one.
- if large then 'accessory R hepatic v.'
- Upper group are the major vein from the liver.A
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Anomolies
Double system up to renal veins.
- can prevent caval filter access
Sometimes the Left renal vein goes behind the aorta, or is paired, sandwiching it.