The posterior tibial vein is a large blood vessel of the leg. One of two major veins of the posterior lower leg, the posterior tibial runs up the medial side of the calf, or the same side as the big toe. It transports deoxygenated blood from veins in the sole of the foot to the popliteal vein, the large vein in the back of the knee. Alongside the posterior tibial vein is the posterior tibial artery, which transports oxygenated blood in the opposite direction.
In the closed loop that is the human circulatory system, arteries carry blood that has been supplied with oxygen in the lungs away from the heart and distribute it throughout the body’s tissues. Veins are the vessels that return the blood to the heart once it has been drained of oxygen, which the tissues require to survive. The two vessels typically run side by side, with one bringing blood to the hands, for example, and a paired vessel returning blood from the hands to the heart.
The posterior tibial vein, along with the peroneal vein near the lateral side of the leg, returns blood from the foot and the posterior compartment of the lower leg. Also referred to as the calf, the posterior compartment of the lower leg includes the muscles, tendons, ligaments, and fat contained in the back of the leg between the knee and the ankle. Smaller veins bring blood from these tissues and deposit it into the peroneal and posterior tibial veins like tributaries feeding a larger river.
Veins from the sole, or plantar surface, of the foot also feed the posterior tibial vein, which originates behind the medial malleolus of the ankle. The medial malleolus is the protrusion of the tibia bone that forms the large bump on the inside of the ankle. Veins beneath the heel converge behind the malleolus near the back of the ankle to form the posterior tibial, which is held in place alongside several ankle tendons and nerves by a broad horizontal ligament called the flexor retinaculum.
The posterior tibial vein shoots up the calf from behind the ankle, with its corresponding artery running directly parallel, until it approaches the back side of the knee. Here it converges with the peroneal vein in the center of the upper calf to form the popliteal vein. A very large blood vessel, the popliteal vein brings the blood from the lower leg vessels up the back of the thigh en route back to the heart.