The arteries of the legs are part of a high-pressure system designed to deliver oxygen-rich blood to the lower limbs. This circulatory journey begins high in the pelvis, where the main vessel, the external iliac artery, crosses a ligament in the groin to become the primary conduit for the entire leg. Tracing the path of these major blood vessels provides a clear map of how the lower limb receives its necessary blood supply, moving from a single large trunk to a complex network of smaller branches down to the toes.
The Major Arterial Trunk: Groin and Thigh
The main pipeline for blood entering the lower limb is the femoral artery, which is the continuation of the external iliac artery from the abdomen. This transition occurs just beneath the inguinal ligament in the groin area, marking the beginning of the arterial supply to the leg itself. The femoral artery is initially quite superficial, making it accessible for feeling a pulse, but also potentially vulnerable to injury in this upper region of the thigh.
As the femoral artery travels down the thigh, it moves from the anterior (front) side toward the medial (inner) side, eventually becoming deeper. A significant branch, the deep femoral artery, or profunda femoris, arises early from the main trunk. This deep vessel is the major supplier for the powerful muscles of the thigh, providing numerous branches that penetrate deep into the tissue.
The main femoral artery continues its course through a muscular tunnel known as the adductor canal, maintaining its role as the primary pathway to the lower leg. The artery shifts from the front of the thigh to the back by passing through an opening in the adductor magnus muscle near the knee.
The Popliteal Region and Calf Divisions
Once the main vessel passes through the opening in the adductor magnus muscle, it enters the space behind the knee, known as the popliteal fossa, and is renamed the popliteal artery. Because of its location deep within this space, surrounded by fat and muscle, the popliteal artery is protected from surface pressure. Its deep position makes its pulse more difficult to feel compared to the femoral artery.
At the lower border of the popliteus muscle, the popliteal artery undergoes a major division, splitting into two primary branches that will supply the rest of the leg. This split creates the anterior tibial artery and the tibioperoneal trunk, which quickly separates into the posterior tibial and fibular arteries.
The anterior tibial artery immediately passes through a small gap in the interosseous membrane, which is the fibrous sheet connecting the tibia and fibula bones. This maneuver moves the artery from the back of the leg to the anterior compartment, where it supplies the muscles responsible for lifting the foot and toes. The posterior tibial artery travels down the back of the calf, supplying the large calf muscles, running close to the tibia bone.
Terminal Circulation and Pulse Points
As the anterior tibial artery reaches the ankle joint, its name changes, and it becomes the dorsalis pedis artery, situated on the top surface of the foot. This vessel runs over the tarsal bones and is the primary artery supplying the dorsal side of the foot. It eventually continues deep into the foot to contribute to the complex arterial arch that supplies the toes.
The posterior tibial artery continues its path down the back of the leg, eventually curving around the bony protrusion on the inner ankle, called the medial malleolus. After passing behind this ankle bone, it enters the sole of the foot, where it divides into the medial and lateral plantar arteries to supply the arch and underside of the foot. This point behind the ankle is a common location to check for circulation.
These two terminal arteries provide important locations for medical professionals to check peripheral circulation through pulse points. The dorsalis pedis pulse is found by gently pressing on the top of the foot, typically along the line between the first and second toes. The posterior tibial pulse is located just behind and slightly below the medial malleolus. Checking these sites allows for a quick assessment of blood flow to the lower extremities.