The Anatomy of the Popliteal Artery

A continuation of the femoral artery in the inner thigh, the popliteal artery travels across the popliteal fossa — the pit behind the knee joint — before terminating into two branches: the anterior and posterior tibial arteries. Along with its many branches, it’s the primary blood supply for the knee joint as well as several major muscle groups in the legs.

Anatomy

The popliteal artery branches off from the femoral artery at the level of the adductor hiatus — the space between the adductor magnus muscle and the femur — in the thigh. It runs down the popliteal fossa, which is the shallow depression behind the knee joint, before traveling between the gastrocnemius and popliteal muscles located on the backside of the lower leg. There it travels deeper into the rear compartment of the leg, where it splits into the anterior and posterior tibial arteries.

There are several major branches:

• Superior Genicular Arteries: At the level of the knee, the popliteal artery splits into the five genicular branches to form the periarticular genicular anastomosis, which provides blood to the joints and tendons there. The superior lateral and medial genicular branches curve around the femoral condyles, which are the two major protrusions at the bottom of the femur.
• Middle Genicular Artery: The middle genicular artery breaks off at the distal femoral intercondylar region — the space between the femoral condyles — running to the front of the kneecap, which it supplies.
• Inferior Genicular Arteries: The inferior lateral and medial genicular arteries run around the tibial condyles — the corresponding gap on the top of the lower leg’s tibia bone — to run deep into the collateral ligaments of the knee. They supply the joint capsule, the collateral ligaments and tendons, and the front part of the anterior cruciate ligament and the inferior part of the patella.      
• Muscular Branches: A major task of the popliteal artery is to supply the muscle groups in and around the lower thigh, knee, and lower leg. This includes the sural arteries, which deliver blood to the hamstring, gastrocnemius and soleus muscles of the calves, as well as the plantaris muscle, a tendon that runs alongside the Achilles. This artery terminates at the two anterior and posterior tibial arteries.

Anatomical Variations

Occasionally, there may be variations in the structure of the popliteal artery. The three most common are:

• Higher Origin of Tibial Artery: In some cases, the terminating branches of the popliteal artery — the posterior and anterior tibial arteries — begin higher than usual.
• Trifurcation: This is when there is a three-way split from the popliteal artery into the anterior tibial artery (serving the front of the lower leg), the posterior tibial artery (serving the rear of the lower leg), and the peroneal artery.  
• Hypoplastic/Aplastic Posterior Tibial Artery: This is a rare case in which there’s an incomplete development of the tibial artery at the end of the popliteal artery.

Function

This artery’s primary job is to deliver blood to the bones and tendons of the knee; it’s the main supplier for that area. In addition, it supplies important hamstring and calf muscle groups, including the gastrocnemius, soleus, and popliteus muscles.

Though its position deep within the popliteal fossa makes it difficult to access, in medical practice its pulse can be felt by having the patient lay down and raise a flexed knee keeping other muscle groups relaxed. When this pulse is absent or weak, it may be a sign of obstruction of the femoral artery.

Clinical Significance

Several conditions are closely related to the health of the popliteal artery.

In cases of knee dislocation, popliteal artery hemorrhage can arise due to the artery’s close proximity to that part of the body. The trauma of the injury causes the artery to stretch, which can lead to contusions, rips, rupture, or complete disconnection from the rest of the circulatory system. Not only can this severely disrupt blood flow in the area, but it can also lead to damage to the calf muscles. Untreated, this can even lead to loss of the limb.

Another condition, popliteal artery entrapment syndrome (PAES), arises when there are variations in the course of the artery as it passes between the two heads of the calf muscle. This leads to pain due to insufficient blood supply when the muscles are contracted, a condition called intermittent claudication. The resulting trauma can lead to thrombosis or thromboembolism, or clotting within the artery, as well as aneurysms (a bulging of the artery).