What Is the Inferior Vena Cava?

The largest venous trunk in the inferior vena cava is the main trunk of the inferior vena cava system. It is synthesized by the left and right common iliac veins at the 5th lumbar plane, rising along the right side of the abdominal aorta, passing through the back of the liver, and passing through the vena cava. The hole enters the chest and into the right atrium. Collect venous blood from lower extremities, pelvis, and abdominal cavity. When the inferior vena cava is occluded, varicose vessels can be seen on both sides of the abdominal wall and below the umbilical plane.

The largest venous trunk in the inferior vena cava is the main trunk of the inferior vena cava system. It is synthesized by the left and right common iliac veins at the 5th lumbar plane, rising along the right side of the abdominal aorta, passing through the back of the liver, and passing through the vena cava. The hole enters the chest and into the right atrium. Collect venous blood from lower extremities, pelvis, and abdominal cavity. When the inferior vena cava is occluded, varicose vessels can be seen on both sides of the abdominal wall and below the umbilical plane.

Chinese name

Inferior vena cava

Foreign name

inferior vena cava

Inferior vena cava anatomy:

1. Inferior vena cava:

The inferior vena cava collects venous blood from the lower body and returns to the right atrium, which is the largest venous trunk in the human body. The 4th to 5th lumbar vertebrae are formed by confluence of the left and right common iliac veins. It rises on the right side of the abdominal aorta, passes through the vena cava fossa of the liver, and then penetrates the vena cava hole of the liver up to the thorax, and is injected into the lower posterior portion of the right atrium. There is a less obvious inferior vena cava valve at the front left of the entrance.

The inferior vena cava is adjacent to the right common iliac artery, the small intestinal mesentery, the right internal spermatic artery, the third segment of the duodenum, the pancreas, the portal vein, and the liver; Arteries, right lumbar artery, right adrenal artery, and right inferior iliac artery are adjacent; the lower left side is accompanied by the abdominal aorta, and the upper side is adjacent to the hepatic tail lobe and the right heel.

The inferior vena cava and its branches form the inferior vena cava system. All veins from the lower limbs, pelvis and abdomen belong to the inferior vena cava system, and they are finally injected into the right atrium through the inferior vena cava.

2. Right ventricle:

The right ventricle has a triangular pyramid shape with a bottom to right atrium opening and a pointed downward. In the ventricular cavity, there is a muscular bulge from the right atrioventricular vent to the pulmonary vent, called the supraventricular condyle. This case divides the right ventricle into the inflow and outflow tracts.

The inflow tract is the main part of the right ventricle, and there are many intersecting muscular bulges on the inner surface of the wall called the meat column. There are several thick and tapered meat columns called papillary muscles, which are generally three in front, back and medial. The entrance of the inflow tract is the right atrioventricular port, and there are three approximately triangular valves at the anterior, posterior, and medial edges of the port, called the tricuspid valve. The bottom of each valve is attached to the fibrous annulus (cardiac bone) around the right ventricular ostium, and its tip, or free edge, is connected to two adjacent papillary muscles by tendon cords. When the ventricle contracts, blood pushes the valve to close the atrioventricular opening. Due to the contraction of the papillary muscles and the tension of the chordae, the valve does not turn into the right atrium, prevents the blood from flowing backward into the atrium, and ensures the directional flow of blood. Any dysfunction such as valves, chordae, papillary muscles, and fibrous rings will have a serious impact on hemodynamics.

The outflow tract is the protruding part of the right ventricle to the upper left, which is called the arterial cone or funnel, and the inner surface of the wall is smooth and meatless. The outlet of the outflow tract is the pulmonary artery. There are three half-moon-shaped valves on the periphery of the mouth, called pulmonary valves. The free edge of the valve coincides with the direction of blood flow and faces the pulmonary artery. When the ventricle dilates, the valve that has been forced into the pulmonary artery presses the valve countercurrently, closing the free edges of the three valves to close the pulmonary artery opening to prevent blood from flowing back to the right ventricle.

Morphological structure of the inferior vena cava:

The inferior vena cava is the main trunk of abdominal, pelvic, and lower limb venous return. It is the largest vein in the human body. At the right front of the 5th lumbar vertebra, the left and right common iliac veins merge. The angle of the junction is about 76 ° on average. The inferior vena cava goes up the right side of the abdominal aorta, passes through the vena cava groove of the liver, and passes through the vena cava hole to the lower part of the right atrium. The total length of the inferior vena cava is 25.7 to 27.1 cm. Tube diameter: The confluence of the left and right common iliac veins is 2.0 cm, the upper edge of the flat left renal vein is 3.1 cm, and the puncture site is 3.4 cm. In front of the inferior vena cava, there are the right common iliac artery, the mesenteric root, the right internal spermatic artery, the horizontal part of the duodenum, the upper part of the pancreas and the duodenum, the free edge of the omentum and its contents The right margin of the naked area behind the liver is adjacent; the back of the inferior vena cava is connected with the lower 3 lumbar vertebrae and the anterior longitudinal ligament, the right inferior iliac artery, the right adrenal artery, the right renal artery and the 3rd and 4th lumbar arteries, and the right celiac ganglia , Right sympathetic trunk, diaphragmatic right foot and right psoas muscle and other structures are connected; the right side of the inferior vena cava has the duodenal descending part, the right kidney, the right ureter and the right hepatic lobe; on the left side, there is the abdominal aorta , Diaphragmatic left foot and hepatic caudate lobe. The inferior vena cava is directly or indirectly injected into the branches of the inferior vena cava through the left and right common iliac veins, and the portal vein collects venous blood from the pelvis, lower limbs, and abdomen.