Inferior Vena Cava

Inferior vena cava - course and tributaries, cavocaval anastomoses

Course

The inferior vena cava is formed by the joining of the common iliac veins (anterolaterally to L5, posterior to right common iliac artery)

The IVC is the largest vein in the body and it has no valves (except for one in the entry to the right atrium, which is non-functional).

Path: runs superiorly, right to the aorta and anteriorly to the psoas major muscle. It passes via the caval opening of the diaphragm to enter the thorax at the level of T8.

Tributaries:

● Hepatic veins (T8)

● Inferior phrenic vein (T8)

● Right suprarenal vein (L1)

● Renal veins (L1)

● Right gonadal vein (L2)

● Lumbar veins (L1 – L5): some drain into the ascending lumbar veins draining into azygous and hemiazygos veins

● Common iliac veins (L5)

Cavocaval anastomoses

Scheme of Cavo-Caval Anastomoses

The cavocaval anastomoses are the connections between the SVC and IVC. Under physiological conditions these connections are minimal.

However, they are clinically significant when one of the veins is occluded. The communication can work both ways.

There are 4 connections between the 2 veins:

• lumbar veins and azygos vein (1):
  • SVC <-> azygos v. <-> azygos v./hemiazygos v. <-> subcostal v. <-> ascending lumbar <-> lumbar v.
• inferior and superior epigastric (2):
  • SVC<-> brachiocephalic <-> internal thoracic <-> superior epigastric <-> inferior epigastric <-> external iliac
• Superficial epigastric and thoraco-epigastric (3):
  • SVC <-> axillary <-> thoraco-epigastric <-> superficial epigastric <-> great saphenofemoral <-> external iliac <-> IVC
• vertebral venous plexus (4) and other veins:
  • The venous plexuses inside the epidural space and the plexuses found, eventually drain into the SVC or IVC