The subclavian vein is a paired large

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

, one on either side of the body, that is responsible for draining

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

from the upper extremities, allowing this blood to return to the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

. The left subclavian vein plays a key role in the absorption of

lipids Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and others. The fu ...

, by allowing products that have been carried by lymph in the thoracic duct to enter the bloodstream. The

diameter In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...

of the subclavian veins is approximately 1–2 cm, depending on the individual.

Structure

Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle. From here it joins with the

internal jugular vein The internal jugular vein is a paired jugular vein that collects blood from the brain and the superficial parts of the face and neck. This vein runs in the carotid sheath with the common carotid artery and vagus nerve. It begins in the posteri ...

to form the brachiocephalic vein (also known as "innominate vein"). The angle of union is termed the venous angle. The subclavian vein follows the subclavian artery and is separated from the subclavian artery by the insertion of anterior scalene. Thus, the subclavian vein lies anterior to the anterior scalene while the subclavian artery lies posterior to the anterior scalene (and anterior to the middle scalene).

Function

The thoracic duct drains into the left subclavian vein, near its junction with the left

. It carries lymph (water and solutes) from the

lymphatic system The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphoid organs, lympha ...

, as well as

chylomicrons Chylomicrons (from the Greek χυλός, chylos, meaning ''juice'' (of plants or animals), and micron, meaning ''small''), also known as ultra low-density lipoproteins (ULDL), are lipoprotein particles that consist of triglycerides (85–92%), ...

chyle Chyle (; ) is a milky bodily fluid consisting of lymph and emulsified fats, or free fatty acids (FFAs). It is formed in the small intestine during digestion of fatty foods, and taken up by lymph vessels specifically known as lacteals. The lip ...

, formed in the

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...

from dietary fat and

, allowing these to enter the bloodstream; the products of fats and

can then be carried by the bloodstream to the hepatic portal vein, and then finally to the liver. Consequently, the left subclavian vein plays a key role in the absorption of these fats and lipids. The right lymphatic duct drains its lymph into the junction of the right internal jugular vein, and the right subclavian vein.

Clinical relevance

Central venous lines

As the subclavian vein is large, central and relatively superficial, the right subclavian vein is often used to place central venous lines. It is less commonly used than other approaches, such as the right

, due to the risk of

pneumothorax A pneumothorax is collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way valve is ...

, haemothorax, and puncture of the accompanying subclavian artery.

Thoracic outlet syndrome

The subclavian vein may be blocked in thoracic outlet syndrome. This can lead to arm swelling,

pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

, and

cyanosis Cyanosis is the change of Tissue (biology), tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Cyanosis is apparent usually in the Tissue (bi ...

. The cause of the thoracic outlet syndrome, whether a

thrombus A thrombus ( thrombi) is a solid or semisolid aggregate from constituents of the blood (platelets, fibrin, red blood cells, white blood cells) within the circulatory system during life. A blood clot is the final product of the blood coagulatio ...

or external pressure, must be removed immediately.

Etymology

''Sub'' (below), and ''clavian'' (pertaining to the

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

Disorders

Paget–Schroetter disease includes the

thrombosis Thrombosis () is the formation of a Thrombus, blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thrombocytes) and fib ...

of the subclavian veins, in this case usually caused by exercise-induced strains.

Additional images

File:First rib Gray.png, Peculiar ribs. File:Venenwinkel.png, The venæ cavæ and azygos veins, with their tributaries. File:Gray599.png, The thoracic and right lymphatic ducts. File:Gray1178.png, The thymus of a full-term infant, exposed in situ. File:Slide9a.JPG, Subclavian vein File:Slide7d.JPG, Subclavian vein - right view File:Slide5dj.JPG, Subclavian vein File:Slide15d.JPG, Subclavian vein

References

{{Authority control Thoracic veins Veins of the torso