Knee Anatomy

The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap).

Knee Anatomy

The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap). The femur and tibia meet to form the knee joint which is a hinge with the knee cap(patella) in front of these two bones acting as a mobile shield to protect the joint. The patella slides up and down in a groove in the femur called the femoral groove as the knee is bent and straightened.

Ligaments hold the knee together and give it stability. The medial (inner) collateral ligament (MCL) and outer (lateral) collateral ligament (LCL) limit sideways motion of the knee. The posterior and anterior cruciate ligaments (PCL and ACL) limit forward and backward translational motion of the knee bones, keeping them stable and allowing the knee to function as a unit.

Two structures known as menisci sit between the femur and the tibia and act as cushions or shock absorbers for the knee. Menisci are one of two types of cartilage in the knee. The other type, articular cartilage, is a smooth and very slick material that covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. This articular cartilage allows the bones to move smoothly without pain. If this layer wears away, it is called arthritis and then the motion becomes painful.

Tendons connect muscles to the bones of the knee. The quadriceps muscles on the front of the thigh are connected to the top of the patella by the quadriceps tendon, which covers the patella and becomes the patellar tendon. The patellar tendon then attaches to the front of the tibia. The hamstring muscles in the back of the leg attach to the leg bone (tibia) at the back of the knee. The quadriceps muscles straighten the knee and the hamstring muscles bend the knee both of which are required for walking, running or simply standing.