The brachial vein is part of an intricate system of veins of the upper limbs. There are two brachial veins in each arm. These veins work together with the brachial arteries to carry blood to and from the heart and the arms. The primary purpose of the vein is to carry carbon dioxide and deoxygenated blood from the muscles in the upper arm to the heart for filtration.
A brachial vein is one of two venae comitantes, which is Latin for accompanying veins, that follow along each side of the brachial artery. The blood in these veins actually runs in the opposite direction of the artery. The artery supplies the arm with freshly pumped blood, while the veins return the deoxygenated blood and carbon dioxide back to the heart. The veins use the momentum of the artery's pulsation to keep the blood moving back to the heart.
Each brachial vein begins at the elbow, where the radial veins and ulnar veins combine to form the brachial artery. They end under the shoulder blade, at the teres major muscle, where they merge with the basilic vein. The basilic vein in turn becomes the axillary vein and continues the blood's path back to the heart.
Smaller veins aid the brachial veins. These tributary veins drain old blood from the muscles in the upper arm. Some of these muscles include the biceps brachii muscle and the triceps brachii muscle to their respective brachial. The smaller, branch-like veins only extract blood, but they follow the same course as the corresponding small veins that carry blood to the muscles.
The brachial vein is classified as a deep vein. A majority of deep veins are also venae comitantes and run with an artery of the same name. Deep veins, including the brachials, carry this classification because they are located deep in the body. Superficial veins are the complementary classification of veins. These veins run close to the surface of the skin.
Some conditions that can affect the brachial vein include trauma and thrombosis. The majority of trauma injuries affecting the brachials are penetrating injuries, like accidents involving glass and stab wounds. Thrombosis can also affect the brachials, although it is much more common in the lower limbs. Thrombosis is a blood clot, and the likelihood of it occurring increases when trauma is present.