Читать книгу Anatomy and Embalming - Charles Otto Dhonau - Страница 51

—The veins are the vessels which carry the blood from the capillaries back to the right auricle of the heart, and are found in nearly every tissue of the body. They commence as venous capillaries, uniting together into larger and larger veins, until we have the great ascending and descending venae cavae. In form the veins are perfectly cylindrical, like the arteries, but with this difference, that their walls collapse when empty and that they contain valves.

Structure.—The vein has about the same structure as the artery, only that the middle coat is much thinner and less elastic than the artery, and for this reason it easily collapses.

Veins are divided into superficial, deep and sinuses. Superficial veins are found between the layers of the superficial fascia, just underneath the skin.

Deep veins accompany the arteries, and are usually enclosed in the same common sheath with the artery.

Sinuses are venous channels, which in their structure and mode of distribution differ altogether from the veins. They are found only in the interior of the skull, and consist of channels formed by a separation of the two layers of the dura mater.

Fig. 11—Human blood.