Anatomy of the Knee


Your knee is one of the largest and one of the most complex joints in the human body. It is a hinge-like joint that allows the leg to bend and extend. It is made up of muscles, cartilage, ligaments, and tendons. The knees provides a number of important functions for the body, like:


  • Help to lower and raise the body
  • Provide stability
  • Act as a shock absorber
  • Allow for twisting of the leg
  • Help propel the body forward


There are three bones that meet in the knee joint – the femur (thigh bone), tibia (shin bone), and patella (kneecap).

The femur is both the longest and the largest bone in the human body and the only bone in the upper leg. The lower portion of the bone creates the upper part of the knee.

The tibia is the second largest bone in the human body. The long, straight bone connects the knee and the ankle.

The patella is a small, triangular bone located at the front of the knee within the quadriceps muscle. Since it endures a lot of force, it is lined with the thickest layer of cartilage in the human body. The patella helps to extend the knee and protect the knee joint from impact.

Articular Cartilage

The articular cartilage is a thin, shiny layer of cartilage that acts as a shock absorber. It also helps the bones move smoothly over each other. Articular cartilage is found on the femur, at the top of the tibia, and the back of the patella.


The menisci are crescent-shaped discs that serve as a cushion so that the bones of the knee can go through their range of motion without rubbing directly against each other. The menisci also have nerves in them, which help improve balance and stability as well as ensure the correct weight distribution between the femur and tibia. There is a lateral meniscus which is located on the outer side of the knee and a medial meniscus located on the inner side of the knee. The medial meniscus is the bigger of the two.

Cruciate Ligaments

There are two cruciate ligaments in the knee, which are tough fibrous tissue. They are like strong ropes that connect bones to each other and prevent too much motion. These ligaments are found inside the knee joint and cross each other to form an “X.” The anterior cruciate ligament (ACL) prevents the femur from sliding backward on the tibia and the tibia from sliding forward on the femur. The posterior cruciate ligament (PCL) prevents the femur from sliding forward on the tibia and the tibia from sliding backward on the femur.

Collateral Ligaments

The collateral ligaments are made of the same tough, fibrous tissue as the cruciate ligaments. These ligaments are located on the sides of your knee. The medial collateral ligament (MCL) and the lateral collateral ligament (LCL) both prevent the femur from moving side to side and brace it against any unusual movement.


Tendons are tough bands of soft tissue that act as stabilizers in the knee. They are similar to ligaments, but connect bone to muscle instead of bone to bone. The biggest tendon in the knee is the patellar tendon. This tendon covers the kneecap and runs up the thigh to attach to the quadriceps.


Bursae are fluid-filled sacs that are found all over the body. There are about 14 of these within the knee joint itself. They serve the important purpose of reducing friction between the tissues of the knee and preventing inflammation.