The Anatomy of the Posterior Tibial Artery

The posterior tibial artery (PTA) is a major artery that delivers blood to certain areas of the lower leg. It can be affected by conditions such as atherosclerosis and far less frequently, chronic compartment syndrome, in which swelling and inflammation of muscles in the calf press on the artery and block blood flow.

This article describes the anatomy of the PTA, explains how it functions in the body, and discusses the health conditions that can affect it.

Anatomy

The popliteal artery give off the anterior tibial artery, and then becomes the tibial peroneal trunk. This then splits into the peroneal artery and the posterior tibial artery. Then, the PTA progresses downward behind the popliteal muscle (a small muscle at the knee joint) and through the soleus muscle. It then passes between a central calf muscle called the tibialis posterior and the flexor digitorum longus, the calf muscle that helps the foot to flex.

The PTA ends at the talus, the bone that makes up the lower half of the ankle joint just above the calcaneus (heel bone).   

Anatomical Variations

As with many parts of the body, the posterior tibial artery sometimes does not look the same in everyone. Variations in the PTA include:

• Hypoplastic or aplastic PTA, in which the artery does not develop fully. This occurs in only around 5% of people. Even less often, in 0.8% of people, both the PTA and the anterior tibial artery (ATA) are hypoplastic.
• Trifurcation, in which a third artery branches off from the popliteal artery in addition to the PTA and ATA
• High origin, which simply means the PTA starts higher up on popliteal artery than normal

Around 13% of the time, when there are variations of the PTA on one leg, the other leg will have the same variations.

Function

The PTA provides blood to the posterior compartment of the leg, which is more commonly known as the calf. There are seven muscles in the calf which, like all muscles, require blood and oxygen to function properly.

The calf muscles that receive oxygenated blood from the PTA are divided into two groups. The flexor hallucis longus, flexor digitorum longus, tibialis posterior, and popliteus muscles are located deep within the calf. The muscles closest to the skin are the ones that give the calf its curved shape. They are the gastrocnemius, soleus, and plantaris muscles.   

The PTA also plays a role in providing blood to the bones of the lower leg—the tibia and fibula.

Clinical Significance

Like most major arteries, a number of health issues can affect the PTA. There are two conditions in particular that may involve the posterior tibial artery.

Peripheral Artery Disease

Peripheral artery disease typically is caused by atherosclerosis. It occurs when plaque—a mixture of cholesterol, other fats, calcium, and inflammatory cells called macrophages—builds up inside an artery.

Plaque can block the flow of blood, which in the case of the PTA. Often if just one of the 3 tibial artery is occluded, there is little clinical significance. However, if all 3 are occluded it can cause ischemia to the area supplied the tibial vessels.

Peripheral artery disease can be treated with medication and, in advanced cases, minor surgical procedures. If peripheral artery disease in the PTA isn't treated, the lack of blood flow to the leg can cause muscle and other tissue to die, a condition known as gangrene. A body part affected by gangrene often must be amputated.

Atherosclerosis in PAD increases the risk of heart attack.

Summary

The posterior tibial artery plays an important role in supplying blood and oxygen to the muscles and bones in the lower leg. It is a continuation of the popliteal artery, which directly connects to the femoral artery.