The human knee is a very interesting joint. It is one of the most used joints of the body and may be used up to one million times per year.
Bones of the knee
If the knee were viewed from the back, with no skin or muscles attached to it, the four bones that make up the knee would be clearly visible. The big bone on the bottom left is the tibia. To the right of that is a much smaller bone called the fibula. The fibula also helps support the knee. At the top of the knee is the thigh bone, also known as the femur. This bone goes all the way up to the hip. The fourth bone that helps make up the knee is the knee cap, or patella. The patella is encased in the tendon of the quadriceps. The quadriceps are the large muscles of the thigh. They are the muscles used to extend the knee and flex the hip. This group of muscles is needed in order for the upper leg to move. These muscles straighten the leg at the knee and keep it straight during standing.
Ligaments of the knee
There are four major ligaments that hold the knee together. Ligaments are tough, fibrous bands that hold bone to bone. The ligaments of the knee hold the bones of the knee together, but they also allow the knee to move. The medial collateral ligament is a thick band that keeps the knee stable when it moves from side to side. Another ligament, called the lateral collateral ligament is on the other side of the knee. The anterior cruciate ligament crosses over the posterior cruciate ligament in the center of the knee.
The menisci are 2 C-shaped disks of cartilage that sit between the thigh bone and the shin bone and act as shock absorbers during walking or running. They also help the knee to flex and extend properly.
Muscles that cross the knee
Among the muscles that cross the knee are the quadriceps muscles. These are the major muscles of the thigh and are made up of four muscle groups. The iliotibial band is a tendon, but it comes from a muscle that is in the hip. It affects the function of the knee cap. The hamstrings run down the back of the thigh and attach at the back of the knee. The calf muscles run up the back of the leg from the heel and cross over the knee, and also attach at back of the knee.
Jointhealing.com explains that the knee joint is encased in a joint capsule which protects it. This joint capsule is lined with tissue called the synovium. The synovium produces a thick liquid called synovial fluid. This fluid protects and nourishes the joint and also lubricates it to keep it moving smoothly.
The knee is indeed an amazing and complex structure. All the parts of it work together to create an effective joint that makes walking, running, and standing possible. A video by Envisionphysio and another by emedtv.com both contain more amazing facts about the wonderful knee.