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- Your knee anatomy
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- Getting diagnosed with osteoarthritis
- Osteoarthritis treatment options
- More information on osteoarthritis
Your knee anatomy
What is the knee joint and what does it do?
Bones of the knee
Ligaments of the knee
Cartilage of the knee
Tendons of the knee
References
The knee is one of the most complex joints of the human body and plays a role in almost all of your movements.
Simply put, the knee works in a fashion similar to a modified hinge on a door. The knee not only bends back and forth like a hinge, but it also has a complex rotational component that occurs whenever you bend (this is called “flexion”) as well as when you straighten it (this is referred to as “extension”). The knee is a major weight-bearing joint that is held together by muscles, ligaments and soft tissue.
Cartilage can be found inside the joint and provides shock absorption, which comes into play whenever you walk, run, lift, climb stairs or perform pretty much any other impact activity you can name. See the illustration below for more on the components of the knee.
Your knee is composed of four main components:
Simply put, the knee works in a fashion similar to a modified hinge on a door. The knee not only bends back and forth like a hinge, but it also has a complex rotational component that occurs whenever you bend (this is called “flexion”) as well as when you straighten it (this is referred to as “extension”). The knee is a major weight-bearing joint that is held together by muscles, ligaments and soft tissue.
Cartilage can be found inside the joint and provides shock absorption, which comes into play whenever you walk, run, lift, climb stairs or perform pretty much any other impact activity you can name. See the illustration below for more on the components of the knee.
Your knee is composed of four main components:
- Bones
- Ligaments
- Cartilage
- Tendons
Your knee is made up of the femur (thighbone), the tibia (shinbone) and the patella (kneecap). The femur and tibia meet to form a hinge with the patella in front of them, which provides protection for the joint. All the while, the patella moves in a sliding action up and down in a groove in the femur. This groove is called the femoral groove, and the sliding occurs whenever you bend or straighten your knees.
The job of the ligaments is to ensure that the components of the knee are held together and kept stable. The medial (inner) collateral ligament (MCL) and lateral (outer) collateral ligament (LCL) limit sideways motion of the knee. At the same time, the posterior and anterior cruciate ligaments (PCL and ACL) limit forward motion of the knee bones, thus keeping them stable. Without this stability, you would feel that your knee is simply giving out from under you.
Each knee has two cartilage structures called menisci, which sit between the femur and the tibia. These strong but flexible menisci act as shock absorbers. They also stabilize and evenly distribute your body weight across the knee joint. Often, a torn meniscus is called “torn cartilage.” The menisci are one of two types of cartilage in the knee. The second type, articular cartilage, is a smooth and very slick material, which covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. All of these parts enable the knee and its bones to move smoothly.
The job of the tendons is to connect muscles to the knee. The quadriceps muscle at the front of the thigh is 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 at the back of the thigh attach to the tibia at the back of the knee. The quadriceps muscles straighten the knee, while the hamstring muscles provide the knee’s bending motion.
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1. SUPARTZ [patient information]. Memphis, TN: Smith & Nephew; 2007.