Popliteus

A small, triangular muscle located at the back of the knee joint.

The popliteus is a thin, flat muscle situated at the posterior aspect of the knee. It originates from the lateral femoral condyle and the posterior horn of the lateral meniscus, with its fibers running diagonally downwards and medially to insert into the tibia's posterior surface above the soleal line. This muscle plays a crucial role in knee joint stability and function.

Terminologia Anatomica

musculus popliteus

System

Musculoskeletal system

Function

The primary function of the popliteus muscle is to initiate the unlocking of the knee from a fully extended position during flexion. As the knee is locked in extension, the femur rotates slightly medially on the tibia. The popliteus, by contracting, facilitates this medial rotation and prevents hyperextension of the knee. Additionally, it provides stability by supporting the lateral side of the knee joint and helping to maintain proper alignment during various movements. Its contribution to the knee's rotational capacity is vital in activities such as walking, running, and changing direction. This muscle also plays a minor role in the slight flexion of the knee and assists in maintaining the intricate balance between the knee's ligamentous structures.

Location

The popliteus is located in the posterior compartment of the knee, nestled between the femur and the tibia. It lies deep to several structures, including the gastrocnemius muscle, the soleus muscle, and the various ligaments surrounding the knee joint. Its position makes it strategically important for knee joint mechanics, as it acts directly at the area where significant movements and forces occur during locomotion. The muscle's attachments and orientation also allow it to play a key role in the transitions between different phases of movement, such as during push-off in walking or running, and while pivoting or turning.

Did You Know?

The popliteus muscle is often referred to as the 'key' to the knee due to its role in unlocking the joint during flexion.
It is considered a significant contributor to preventing so-called 'knee injuries' by providing dynamic stability to the joint.
Despite its small size, the popliteus muscle has a considerable impact on the biomechanics of the knee, making it an essential muscle for athletes.