The anterior cruciate ligament (ACL) is a main stabilizing structure in the knee. Working together with other major knee structures such as the meniscus, posterior cruciate ligament (PCL), collateral ligaments, quadriceps and hamstrings, the knee can function properly. The absence of one of these structures can cause damage to the others, leading to pain and early onset arthritis (think arthritis when you’re in your twenties, here, people) not to mention instability. Here, we’ll talk about these structures and their function.
Check out Sportsmetrics Knee Anatomy Video
The ACL is located in the center of the knee joint. It is called a ‘cruciate’ ligament because it forms a cross with the posterior cruciate ligament (PCL). The purpose of the ACL is to keep the knee joint centered by preventing the shinbone (tibia) from sliding forward. The PCL does the opposite in preventing the shin bone from sliding backward.
The meniscus is cartilage that lines the knee joint and acts as a sort of ‘tray’ between the end of the thigh bone (femur) and the top of the shin bone (tibia) to keep them cushioned, lubricated, and centered. Damage to this tissue is very difficult to repair and can lead to early-onset arthritis.
The Quadriceps muscles are located on the top of the thigh and serve to extend (straighten) the knee. It is counteracted by the hamstrings.
The Hamstring muscles are located on the back of the thigh and serve to bend the knee. In females, the strength of this muscle is often minuscule compared to the quadriceps, creating an imbalance that is dangerous for the ACL.
The medial-collateral ligament (MCL) and lateral-collateral ligament (LCL) are located on the inside and outside edges of the knee, respectively. They serve to help keep the knee centered.
