出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/01/14 11:07:00」(JST)
| Inferior vena cava | |
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Superior vena cava, inferior vena cava, azygos vein and their tributaries
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| Details | |
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Source
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common iliac vein lumbar veins |
| Drains to | heart |
| Artery | abdominal aorta |
| Identifiers | |
| Latin | vena cava inferior |
| MeSH | A07.231.908.949.648 |
| TA | A12.3.09.001 |
| FMA | 10951 |
| Anatomical terminology
[edit on Wikidata]
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The inferior vena cava (or IVC) (Latin: vena, "vein", cavus, "hollow") is a large vein that carries deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the fifth lumbar vertebra.
The inferior vena cava is the lower ("inferior") of the two venae cavae, the two large veins that carry deoxygenated blood from the body: the inferior vena cava carries blood from the lower half of the body whilst the superior vena cava carries blood from the upper half of the body.
It is a large retroperitoneal vein that lies posterior to the abdominal cavity and runs along the right side of the vertebral column. It enters the right atrium at the lower right, back side of the heart.
The inferior vena cava is formed by the joining of the left and right common iliac veins and brings collected blood into the right atrium of the heart. It also joins with the azygos vein (which runs on the right side of the vertebral column) and venous plexuses next to the spinal cord.
The inferior vena cava begins as the left and right common iliac veins behind the abdomen unite, at about the level of L5. It passes through the thoracic diaphragm at the caval opening at the level of T8.
The specific levels of the tributaries are as follows:
| Level | Vein |
| T8 | hepatic veins, inferior phrenic vein |
| L1 | right suprarenal vein, renal veins |
| L2 | right gonadal vein |
| L1–L5 | lumbar veins |
| L5 | common iliac veins |
Because the inferior vena cava is located to the right of the midline, drainage of the tributaries is not always symmetrical. On the right, the gonadal veins and suprarenal veins drain into the inferior vena cava directly. On the left, they drain into the renal vein which in turn drains into the inferior vena cava. By contrast, all the lumbar veins and hepatic veins usually drain directly into the inferior vena cava.
In the embryo, the inferior vena cava and right atrium are separated by the valve of the inferior vena cava, also known as the Eustachian valve. In the adult, this valve typically has totally regressed or remains as a small fold of endocardium.[1]
Rarely, the inferior vena cava may vary in its size and position. In transposition of the great arteries the inferior vena cava may lie on the left. It may be replaced by two vessels beneath the level of the renal veins.[2]
The inferior vena cava is a vein. It carries deoxygenated blood from the lower half of the body to the right atrium of the heart.[2]
The corresponding vein that carries deoxygenated blood from the upper half of the body is the superior vena cava.
Health problems attributed to the IVC are most often associated with it being compressed (ruptures are rare because it has a low intraluminal pressure). Typical sources of external pressure are an enlarged aorta (abdominal aortic aneurysm), the gravid uterus (aortocaval compression syndrome) and abdominal maligancies, such as colorectal cancer, renal cell carcinoma and ovarian cancer. Since the inferior vena cava is primarily a right-sided structure, unconscious pregnant women should be turned on to their left side (the recovery position), to relieve pressure on it and facilitate venous return {{citation needed}}. In rare cases, straining associated with defecation can lead to restricted blood flow through the IVC and result in syncope (fainting).[3]
Blockage of the inferior vena cava is rare, and is treated urgently as a life-threatening condition. It is associated with deep vein thrombosis, IVC filters, liver transplantation and surgical procedures such as the insertion of a catheter in the femoral vein in the groin.[4]
Trauma to the vena cava can also be life-threatening as excessive blood loss may occur.
Inferior vena cava
Inferior vena cava front view
Veins of the abdomen and pelvis
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| To azygos system |
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| IVC (Systemic) |
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| Portal vein (Portal) |
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| リンク元 | 「下大静脈」「postcaval vein」「vena cava inferior」「IVC」 |
| 拡張検索 | 「inferior vena cava interruption with azygos connection」「placement of inferior vena cava filter」 |
| 関連記事 | 「inferior」「inferio」「cava」「vena cava」「vena」 |
| 右房圧 | 下大静脈径 | 呼吸性変動 |
| 5mmHg | ≦18mm | あり |
| 10mmHg | ≧18mm | あり |
| 15mmHg | なし |
Henry Gray (1825-1861). Anatomy of the Human Body. 1918.
Henry Gray (1825-1861). Anatomy of the Human Body. 1918.