Variants and anomalies of veins

The anomaly and topography of veins are more variable than those of arteries.

The superior vena cava may have the right superior pulmonary vein, the right internal thoracic vein, and the right superior intercostal vein as rare, non-permanent tributaries. Rarely, there is a paired (right and left) superior vena cava, in which case the superior vena cava is formed from the left brachiocephalic and hemiazygos veins. Sometimes, the left common venous (Cuvier's) duct is preserved, connecting the left brachiocephalic vein with the coronary sinus of the heart. In some cases, there is a connection between the tributaries of the superior vena cava and the pulmonary veins.

The azygos and hemiazygos veins vary in caliber, topography, and the severity of their tributaries. Sometimes the hemiazygos vein flows into the azygos vein with 2-3 trunks. The level at which the hemiazygos vein flows into the azygos is variable: in 20% of cases it flows at the level of the 6th thoracic vertebra, in 6% - the 7th thoracic, in 14% - the 8th thoracic, and in other cases - at the level of the 9th-11th thoracic vertebrae. The accessory hemiazygos vein is sometimes absent.

The tributaries of the internal jugular vein sometimes include the superior thyroid vein and some tributaries of the lingual vein. The diploic and emissary veins in elderly and senile people sometimes disappear. The tributaries of the facial vein are often poorly expressed. The tributaries of the external jugular vein are inconstant, its anterior tributary-anastomosis with the retromandibular vein (posterior tributary) may be absent. The external jugular vein can form at the posterior edge of the sternocleidomastoid muscle. Sometimes the tributaries of the facial vein, lingual veins, additional internal jugular vein, and the vein of the mammary gland, located subcutaneously, flow into the internal jugular vein. There is an unpaired middle vein of the neck, which passes subcutaneously in front of the trachea. The anterior jugular veins are very variable in number and topography.

The subclavian vein sometimes passes together with the subclavian artery in the interscalene space. The superficial vertical (longitudinal) vein of the neck and the right superior intercostal vein are inconstant tributaries of the subclavian vein. Rarely, the subclavian vein is double.

The brachiocephalic veins vary in the number and direction of their tributaries. Sometimes the axillary vein flows into the brachiocephalic vein. Rarely, the subclavian and internal jugular veins open into the brachiocephalic vein separately. Rarely, the brachiocephalic vein forms local expansions alternating with its narrow sections.

Occasionally, two axillary veins are found - medial and lateral, running parallel, in places connecting with each other by anastomoses. The number of brachial veins can vary from one to four. The severity of their topography is very variable.

The lateral saphenous vein of the arm may be absent, sometimes doubled. The medial saphenous vein of the arm sometimes runs directly under the fascia of the forearm and shoulder, and may flow into the axillary vein. The topography of the connections between the lateral and medial saphenous veins is extremely variable. The following most common forms of intervenous connections of the superficial veins of the forearm are described.

1. The lateral saphenous vein of the arm runs obliquely upward through the cubital fossa, and flows into the medial saphenous vein of the arm at the level of the lower third of the shoulder. The intermediate vein of the elbow is absent, the intermediate vein of the forearm flows into the confluence of the lateral and medial saphenous veins or into one of them.
2. Sometimes there is a significantly developed intermediate vein of the forearm. It can bifurcate, flowing in two parts separately into the lateral and medial subcutaneous veins of the arm or, without dividing, opening into one of them. It is possible for the intermediate vein of the forearm to flow directly into one of the brachial veins. The diameter and number of deep veins of the forearm are variable.

The inferior vena cava is rarely doubled. Its tributaries may be additional renal veins, individual thin tributaries of the portal vein.

The hepatic veins sometimes form one short trunk - the common hepatic vein, which flows into the right atrium, while the inferior vena cava opens into the azygos or umbilical vein. The umbilical vein is often preserved throughout its length, draining blood into the inferior vena cava. The number and diameter of the renal and testicular (ovarian) veins are variable. The number of lumbar veins can range from one to six.

The common, external and internal iliac veins may form local dilatations.

The great saphenous vein of the leg is sometimes very thin, often doubled, less often tripled. Sometimes the small saphenous vein of the leg flows into it. There is often an additional saphenous vein of the thigh, collecting blood from the medial or posterior side of the thigh. This vein flows into the great saphenous vein of the leg and very rarely independently into the femoral vein. There is a saphenous vein located on the lateral surface of the thigh. It flows into the great saphenous vein of the leg near the subcutaneous cleft, the so-called oval fossa. Sometimes there are two trunks of the small saphenous vein of the leg, connected by numerous transverse anastomoses. The small saphenous vein of the leg can flow into the great saphenous vein or into the deep vein of the thigh.

The popliteal and femoral veins are sometimes doubled. The severity of their tributaries is variable.

The portal vein has different lengths and diameters. Its additional tributaries are the accessory splenic, pancreaticoduodenal, and right gastroepiploic veins. The short trunk of the pancreaticoduodenal vein sometimes flows into the superior mesenteric vein. Veins of the cardiac part of the stomach often open into the splenic vein.