Collateral circulation. Anastomosis. Collateral

Collateral circulation. Anastomosis. Collateral

Collateral circulation is an important functional adaptation of the body, associated with the high plasticity of blood vessels and ensuring uninterrupted blood supply to organs and tissues. His deep study, which has important practical significance, is connected with the name of V.N. Tonkov and his school.

By collateral circulation is meant a lateral, roundabout blood flow through the lateral vessels. It takes place under physiological conditions with temporary impairment of blood flow (for example, when blood vessels are compressed in places of movement, in joints). It can also occur in pathological conditions during blockage, injuries, ligation of vessels during operations, etc.

Under physiological conditions, a roundabout flow of blood is carried out along lateral anastomoses running parallel to the main one. These lateral vessels are called collaterals (for example, a. Collateralis ulnaris, etc.), hence the name of the bloodstream “roundabout”, or collateral, circulation.

When blood flow is obstructed through the main vessels, caused by blockage, damage or ligation during operations, the blood rushes through the anastomoses into the nearest lateral vessels, which expand and become crimped, their vascular wall is rebuilt due to changes in the muscle membrane and elastic frame and they are gradually transformed into collaterals other structure than normal.

Thus, collaterals exist under normal conditions, and can develop again in the presence of anastomoses. Consequently, in case of breakdown of the normal blood circulation caused by an obstacle to the flow of blood in a given vessel, the existing bypass circulatory pathways, the collaterals, first turn on, and then new ones develop. As a result, impaired blood circulation is restored. In this process, an important role is played by the nervous system.

From the above follows the need to clearly define the difference between anastomoses and collaterals.

Anastomosis (from the Greek. Anastomos – I supply the mouth) – fistula, every third vessel that connects the other two; This concept is anatomical.

Collateral (from lat. Collateralis – side) – side vessel carrying out a roundabout flow of blood; The concept of this anatomical and physiological.
Collaterals are of two kinds. Some exist in the norm and have the structure of a normal vessel, as well as the anastomosis. Others develop again from the anastomoses and acquire a special structure.

To understand the collateral circulation, it is necessary to know those anastomoses that interconnect systems of different vessels, which establish a collateral flow of blood in the event of vascular injuries, ligation during operations and blockage (thrombosis and embolism).

Anastomoses between the branches of large arterial highways supplying the main parts of the body (aorta, carotid arteries, subclavian, iliac, etc.) and representing, as it were, separate vascular systems, are called intersystem ones. Anastomoses between the branches of one large arterial highway, limited to the limits of its branching, are called intrasystem. These anastomoses have already been noted in the course of the presentation of the arteries.

There are anastomoses and between the thinnest intraorgan arteries and veins – arteriovenous anastomoses. According to them, blood flows around the microcirculatory bed when it overflows and, thus, forms a collateral path directly connecting the arteries and veins, bypassing the capillaries.

In addition, thin arteries and veins accompanying the great vessels in the neurovascular bundles and constituting the so-called perivascular and circulatory arterial and venous channels take part in the collateral circulation.

Anastomoses, besides their practical significance, are an expression of the unity of the arterial system, which, for the convenience of studying, we artificially divide into separate parts.

Leave a Reply

Your email address will not be published. Required fields are marked *