Hemiazygos vein

The Hemiazygos vein is a vein continuation of one of the longest veins in the body. It runs cranially to the diaphragm. Its tasks include the transport of venous blood to the azygos vein.

What is the hemiazygous vein?

The blood in the body circulates in the body and is transported through blood vessels. These blood vessels are veins. In them the blood flows back to the heart. Venous blood is characterized by the fact that it is particularly low in oxygen.

Some veins have to carry the blood against gravity. The hemiazygos vein is also oriented cranially, i.e. upwards, in the thoracic spine area.

The hemiazygos vein is a branch of the ascending lumbar vein. These are veins that run along the trunk of the spine. They are particularly long compared to other veins in the human body. The hemiazygos vein branches off along the thoracic spine and through the thoracic cavity. Almost all human organs are located there. In the area of ​​the chest cavity, the hemiazygos vein accepts other veins and then flows into the azygos vein. This transports the venous blood cranial to the diaphragm to the superior vena cava. This is one of the largest veins in the human body. Your blood stream runs from your head and neck through your upper extremities to your heart.

Anatomy & structure

Starting in the thoracic vertebral area, the hemiazygos vein pulls along the left thoracic vertebrae. Then it runs to the diaphragm. It takes the way there through the medial lumbar gap. At this point it gets from the abdomen to the chest of the human organism. The hemiazygous vein runs from the chest cavity into the posterior chest cavity.

The chest cavity is called the mediastinum. With the exception of the lungs, all organs are located in it. The hemiazygos vein extends from the thoracic cavity to the area of ​​the thoracic vertebrae. There are twelve numbered thoracic vertebrae along the thoracic spine. The hemiazygos vein runs to the ninth thoracic vertebra. The direction at this point of the vein is cranial. This means that it is anatomically oriented in the direction of the head or "upwards".

At the level of the ninth thoracic vertebrae, the hemiazygos vein takes up the bronchial vein. In addition, the posterior intercostal veins and the oesophageal veins flow into it. It then crosses to the opposite side in the region between the seventh and ninth thoracic vertebrae. Here the hemiazygos vein joins the azygos vein.

Function & tasks

The blood is important for the oxygen supply of the tissue and the removal of CO2. In addition, nutrients and hormones are transported to their destination. The body's heat regulation takes place via the blood. All of these functions are performed by the venous blood of the hemiazygos vein.

All types of veins are ideal for infusions. Through a parenteral supply of fluids and medication, they quickly get into the blood and are quickly transported to the appropriate locations via the bloodstream. There they can develop their effect. The wall of the veins is thinner than that of the arteries because their layers are less distinct. For this reason, they are often used for supplying and withdrawing blood. Even if the hemiazygous vein is less suitable for infusions or the supply of blood, it is nevertheless directly and essentially involved in the rapid transport of the messenger substances absorbed, since it runs in the chest cavity along all organs except the lungs.

The hemiazygos vein is part of a bypass circuit. It is connected to the azygous vein and the ascending lumbar vein. This in turn is connected to the inferior and superior vena cava. Together they can form a circuit between the two vena cava. This is known as the collateral circuit and represents a bypass circuit. It is also known as a cavocaval anastomosis. In this case, the collateral circulation arises physiologically, but can also develop in the case of acute or chronic disturbance of the blood flow through the use of secondary vessels.

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Diseases

The wall of the veins is thin. This makes it prone to lesions and diseases.

If the hemiazygous vein is damaged, the supply of important organs and the lumbar spine is restricted. Common venous disorders are venous thrombosis or thrombophlebitis. Thrombophlebitis is inflammation of the veins. This is accompanied by the formation of a blood clot. The patient feels pulling pains and feelings of tension in the affected area. There is severe pain when the vein is pressed. If, for example, the blood clot detaches from the vein, it is transported directly to the heart in the venous blood stream. It then goes to the lungs. There the thrombus blocks a blood vessel and causes a life-threatening pulmonary embolism.

In the healing process of inflammation of the venous wall, persistent occlusions and permanent damage to the venous valves can occur. Overall, this leads to a malfunction of the venous system.

In diseases like cancer, the veins play an important role. Cancer cells that separate from the original tumor are transported to other parts of the body via the bloodstream. This is where metastases develop and the cancer spreads. The hemiazygous vein is involved in a bypass circuit. Cancer cells can then be transported to the organs within the chest.