Human Anatomy: Part 2 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2008

Special Part
Cardiovascular system, systema cardiovasculare — Venous system
Veins of the systemic circulation — Major venous anastomoses of the human body

The venous collectors—the superior and inferior venae cavae—are interconnected by lateral venous anastomoses present in every human. They are termed intersystemic or cava-caval anastomoses, anastomoses cavae-cavales (Fig. 78). These anastomoses become particularly critical when venous return through the superior or INFERIOR VENA CAVA is impaired.

The HEPATIC PORTAL VEIN, v. portae hepatis, anastomoses via its tributaries with the roots of the superior and inferior venae cavae, forming the so-called portacaval anastomoses, anastomoses portocavales. These anastomoses play a vital role when Blood outflow through the portal vein is obstructed in certain conditions (such as Liver cirrhosis, portal Hypertension, and obliterating endophlebitis).

Class="center">Cava-caval anastomoses, anastomoses cavacavales

1. Cava-caval anastomoses along the posterior trunk wall. The cava-caval anastomosis via the azygos vein, v. azygos: the inferior vena cava communicates with the SUPERIOR VENA CAVA via the lumbar Veins, vv. lumbales, and subsequently the ascending lumbar vein, v. lumbales ascendens, which continue into the azygos vein (on the right) and the hemiazygos vein (on the left).

2. Cava-caval anastomosis around THE Vertebral Column. Located on the posterior trunk wall, this anastomosis between the superior and inferior venae cavae is formed by the vertebral venous plexuses, plexus venosi vertebrales. In the cervical region of the vertebral column, these plexuses connect with the VEINS OF THE HEAD and Neck, which are tributaries of the superior vena cava. In the lower region of the vertebral column, the vertebral plexuses anastomose with the lumbar veins, which are tributaries of the inferior vena cava.

3. Cava-caval anastomosis along the anterior abdominal wall. The veins of the anterior abdominal wall (vv. epigastricae superiores and vv. thoracoepigastricae), which are tributaries of the superior vena cava in the umbilical region, regio umbilicalis, anastomose with vv. epigastricae inferiores and epigastricae superficiales, which are tributaries of the inferior vena cava.

Portacaval anastomoses, anastomoses portocavales

The following anatomical portacaval anastomoses are distinguished:

Anastomoses of the hepatic portal vein with the superior vena cava and anastomoses of the hepatic portal vein with the inferior vena cava (Fig. 78).

1. Portacaval anastomoses with the superior vena cava

1.1. Portacaval anastomosis in the lower Esophagus. Venous blood from the hepatic portal vein reverses direction into the gastric veins, vv. gastricae sinistrae, which anastomose with the esophageal veins, vv. esophageae. The esophageal veins then drain into the azygos vein, v. azygos, and the hemiazygos vein, v. hemiazygos, which are tributaries of the superior vena cava.

1.2. Portacaval anastomosis via the venous plexus of the anterior abdominal wall. In the umbilical region, the paraumbilical veins, vv. paraumbilicales (tributaries of the v. portae), anastomose with the internal thoracic vein, v. thoracica interna, and the brachiocephalic vein, v. brachiocephalica (tributaries of the v. cava superior). Blood flows from the hepatic portal vein into the paraumbilical veins, and subsequently via the v. thoracica interna and v. brachiocephalica into the superior vena cava.

1.3. Portacaval anastomosis via the thoracoepigastric vein, v. thoracoepigastrica. The hepatic portal vein, v. portae hepatis, through the paraumbilical veins and plexus umbilicalis, anastomoses with the v. thoracoepigastrica, draining into the axillary vein, v. axillaris, subclavian vein, v. subclavia, brachiocephalic vein, v. brachiocephalica, and ultimately into the superior vena cava.

2. Portacaval anastomoses with the inferior vena cava

2.1. Portacaval anastomosis via the rectal venous plexus, plexus rectalis. In the lower section of the rectal wall, the superior rectal vein, v. rectalis superior—which empties into the hepatic portal vein via the inferior mesenteric vein—anastomoses with the middle and inferior rectal veins, v. rectalis media et v. rectalis inferior, which are Branches of the internal iliac vein. Venous blood from the portal vein flows retrogradely into the v. mesenterica inferior, then into the v. rectalis superior, and via the anastomosis with the vv. rectales mediae et inferiores drains into the common iliac and inferior venae cavae.

Fig. 78. Anastomoses between the superior and inferior venae cavae (cava-caval) and anastomoses of the hepatic portal vein with the inferior and superior venae cavae (portacaval)

2.2. Portacaval anastomosis via the venous plexus of the anterior abdominal wall. The hepatic portal vein, v. portae hepatis, via the paraumbilical veins, vv. paraumbilicales, anastomoses with the inferior epigastric vein, v. epigastrica inferior, and the superficial epigastric veins, vv. epigastricae superficiales, which empty into the external iliac vein, v. iliaca externa (a tributary of the v. cava inferior).

2.3. Portacaval anastomosis via the renal capsule veins. The veins of the renal capsule anastomose with branches of the splenic and inferior mesenteric veins on one side, and with the renal veins on the other, forming portacaval anastomoses on the posterior abdominal wall.