The popliteal artery is a continuation of the femoral artery, beginning at the adductor hiatus. It passes through the popliteal fossa, a diamond-shaped region behind the knee. Within this fossa, the artery is the deepest structure, lying superficial to the popliteus muscle.
The popliteal artery’s position within the fossa is consistent relative to other structures. It lies anterior to the popliteal vein, which is anterior to the tibial nerve, the most superficial of these structures. The artery typically terminates at the lower border of the popliteus muscle, where it divides into its main terminal branches.
Muscular and Cutaneous Branches
The sural arteries are notable muscular branches that consistently originate directly from the popliteal artery. These include a medial and a lateral sural artery. They primarily supply the large gastrocnemius muscle, penetrating deeply to provide its vascular supply.
These arteries also give off perforating branches to nourish the overlying skin of the calf. In addition to the sural arteries, the popliteal artery provides other smaller, unnamed muscular branches that supply adjacent muscles such as the soleus, plantaris, and parts of the hamstring muscles.
The Genicular Arteries and Anastomosis
A network of five genicular arteries arises from the popliteal artery to supply the knee joint and its surrounding structures. These include the superior lateral, superior medial, middle, inferior lateral, and inferior medial genicular arteries. The superior medial genicular artery, for instance, courses anterior to the semimembranosus and semitendinosus, while the superior lateral genicular artery passes above the lateral femoral condyle.
The middle genicular artery uniquely pierces the oblique popliteal ligament to supply the internal structures of the knee, such as the cruciate ligaments and synovial membrane. The inferior medial genicular artery descends with the popliteus muscle before passing the medial tibial condyle, and the inferior lateral genicular artery travels under the gastrocnemius. These genicular arteries are interconnected, forming a collateral circulatory network known as the genicular anastomosis. This network also receives contributions from the descending genicular artery, a branch of the femoral artery, and the anterior tibial recurrent artery, a branch of the anterior tibial artery. This arrangement ensures continuous blood flow to the lower leg, even during knee flexion, which might otherwise compress the main popliteal artery.
Terminal Bifurcation
At the lower border of the popliteus muscle, the popliteal artery concludes its journey by dividing into its two main terminal branches. This division marks the beginning of the arterial supply to the lower leg compartments.
These two terminal branches are the anterior tibial artery and the posterior tibial artery. The anterior tibial artery supplies the anterior compartment of the leg. The posterior tibial artery supplies the posterior compartment. A common trunk for the posterior tibial and peroneal arteries is often observed, with the peroneal artery branching off the posterior tibial artery to supply the lateral compartment.
Clinical Significance of the Popliteal Artery
The popliteal artery’s position makes it susceptible to several conditions. A popliteal artery aneurysm is an abnormal dilation of the artery wall, often defined as more than 1.5 times the normal diameter. These are the most common peripheral aneurysms, often occurring bilaterally and frequently accompanying abdominal aortic aneurysms. They pose a risk of blood clot formation, which can lead to blockages and potentially severe complications such as limb ischemia or, rarely, rupture.
Popliteal artery entrapment syndrome (PAES) occurs when the artery is compressed by surrounding muscles, particularly the gastrocnemius. This compression reduces blood flow, especially during muscle contraction, causing pain and potential arterial trauma. The popliteal artery is also relevant in peripheral artery disease (PAD), a condition caused by atherosclerosis, where plaque buildup narrows the arteries and restricts blood flow to the limbs. Its deep location and the presence of a collateral network around the knee influence how these conditions present and are managed.