Knee Anatomy



The bones of the knee include the femur, tibia and patella (the kneecap). The femur and tibia meet at the knee, where the patella in the front protects the joint. The patella slides up and down in a groove on the femur as the knee is flexed and extended.



The ligaments in the knee hold it together and give it stability. The medial collateral ligament (MCL) on the inner side and the lateral collateral ligament (LCL) on the outer side, limit the sideways motion of the knee. The posterior cruciate ligament (PCL) and the anterior cruciate ligament (ACL) limit forward and backward movment of the femur so the knee stays stable.



Two structures between the femur and the tibia serve as cushions or shock absorbers for the knees. They are known as menisci. When someone refers to having "torn cartilage", this is usually what they are referring to. The other type of cartilage, articular cartilage, is a smooth material that covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. This cartilage allows the bones to move smoothly.