Subclavian Vein: Structure, Function & Diseases

The subclavian vein, also called the subclavian vein, runs behind the collarbone above the first rib. It carries blood from the arm toward the heart.

What is the subclavian vein?

The subclavian vein is one of the veins of the small systemic circulation in the arm and neck. A distinction is made between the right and left subclavian veins. It is one of the root veins of the brachiocephalic vein. Primarily, it transports blood from the upper extremities with the arm and shoulder and enters the right atrium through the brachiocephalic vein (head and arm vein) via the venous angle. From there, the blood flows to the lungs via the pulmonary circulation (small circulation) and is oxygenated. The oxygenated blood flows into the left atrium of the heart and from there is pumped back into the body through the aorta (large artery) to supply oxygen to the tissues (large circulation). Almost all arteries carry oxygenated blood and most veins carry deoxygenated blood. Venous blood is dark red compared to arterial blood because oxygen has been removed. The blood pressure in the veins is much lower than that in the arteries and is called the low-pressure system of the circulatory system.

Anatomy and structure

The subclavian vein, only a few centimeters long, runs horizontally toward the center of the body. It is a companion vein that runs parallel to its corresponding artery (subclavian artery). Also a paired artery, it carries oxygenated blood from the heart back to the head, neck, arm and shoulder. The subclavian vein is the direct continuation of the axillary vein. This, in turn, is a continuation of the brachial vein (arm vein), although the transition is not clearly defined anatomically. Together, the subclavian and axillary veins form the main trunk of the brachial veins. The subclavian vein and the internal jugular vein (internal jugular vein, vein of the neck), which is important for blood drainage from the brain, are both root veins. They join at the angle of the vein to form the brachiocephalic vein (head and arm vein). It is also a paired body vein, with the slightly shorter right portion meeting the left brachiocephalic vein at the level of the first costal cartilage. Here, the two veins join to form the superior vena cava (superior vena cava), which ends in the right atrium of the heart. It is the largest vein in the human body. The subclavian vein is firmly attached to an enveloping layer of connective tissue (fascia clavipectoralis) on the periosteum (periosteum) of the clavicle. This prevents the vein from collapsing (collapsing) and promotes the drawing of blood from the outer zone of the body (periphery) during arm and shoulder movements.

Function and tasks

The subclavian vein is responsible for transporting deoxygenated blood from the arms, shoulders, and lateral chest wall. Blood flow passes through the angle of the vein, to the veins of the head and arms, and finally through the superior vena cava to the right ventricle of the heart. From there, blood is pumped through the pulmonary valves into the pulmonary artery and then into the lungs. In the lungs, the blood is oxygenated and flows back through the mitral valve to the left ventricle. From there, it passes through the aortic valve and into the aorta, where it is distributed throughout the body via the capillaries. The subclavian vein receives its inflow from the external jugular vein, which is formed behind the ear by the union of the occipital vein and the auricular vein. It receives further inflow through the accompanying veins of the subclavian artery. There are functional differences between the right and left subclavian veins. The left side is somewhat more significant because, among other things, the lymphatic collecting trunk, which transports lymph from the entire lower half of the body, enters here. Ani the right side is a small lymphatic vessel that carries lymph from the right arm, the right side of the chest, and the right side of the neck. The lymphatic system specializes in the transport of nutrients and waste products and, along with the circulatory system, forms the most important transport system in the body.

Diseases

Thoracic-outlet syndrome is a compression (contusion) of the vascular nerve bundle consisting of the brachial plexus (brachial plexus), subclavian artery, and subclavian vein.This bundle of vascular nerves must negotiate three constrictions on its way toward the upper extremity: the scalenus gap (denotes the gap between the costoclavicular muscles), the costoclavicular space (the space between the first rib and the clavicle), and the coracopectoral space (the space between the spinous process of the scapula and the pectoral small muscle). A special form of thoracic-outlet syndrome, is thoracic-inlet syndrome. It refers to constriction of the subclavian vein and can lead to subclavian thrombosis or acute axillary venous congestion (Paget-von-Schroetter syndrome). Subclavian vein thrombosis is uncommon compared with leg and pelvic thrombosis. A thrombosis is a blood clot (thrombus) that narrows or blocks the vessels. It occurs when there is not enough venous blood flowing to the heart. Often, thrombosis of the subclavian vein occurs as a result of physical exertion during sports or “overhead” activity. However, it can also occur due to a tumor or a central venous catheter. It usually affects young adult males. The thrombosis occurs predominantly on the right side. A rather rare clinical picture is phlegmasia coerulea dolens. An abrupt onset of complete occlusion of all veins of an extremity (thrombosis). The reason is a disturbance of the microcirculation (part of the blood circulation of the smallest blood vessels). Phlegmasia coerules dolens is an emergency and requires rapid surgical intervention.