Knee joint anatomy involves looking at each of the different structures in and around the knee.
The knee joint is the largest and one of the most complex joints in the human body.
There are various muscles that control movement, ligaments that give stability, special cartilage to absorb pressure and various other structures to ensure smooth, pain-free movement.
Knee pain is a common problem that affects people at all ages. Many different things can go wrong with the knee.
So let's find out all about how the knee joint fits together and works.
In technical terms, the knee is a synovial hinge joint, but what does that mean?
A synovial joint has a joint capsule which is like a sac surrounding the joint. The capsule contains synovial fluid which nourishes and lubricates the joint allowing it to move smoothly and painlessly - a bit like the oil in your car.
A hinge joint typically allows motion in one plane, flexion and extension. The knee is the largest hinge joint in the body and is slightly unusual as it also allows a small amount of rotation.
So let's have a look at the different structures that are part of knee joint anatomy, how they work and how they fit together.
The most basic component of knee joint anatomy are the bones which provide the structure to the knee.
The four knee bones fit together to make two different knee joints:
The knee bones work together to support the body and transfer forces between the hip and foot, allowing the leg to move smoothly and efficiently.
The human knee actually comprises of two joints, the
You can find out all about the different bones and joints that make up the knee, how they function and what can go wrong in the knee bones section.
A really important part of knee joint anatomy is the cartilage. There are two types of cartilage in the knee:
The knee meniscus is particularly important as it acts as a shock absorber to reduce the forces going through the bones and reduces friction, allowing the bones to move smoothly.
The back of the patella is also lined with cartilage, the thickest in the whole body due to the immense forces that go through the kneecap.
You can find out all about the different types of knee cartilage, how they work, and cartilage injuries and how to treat them in the knee cartilage section.
So what about knee muscle anatomy? The main knee muscles controlling the leg are the:
Weakness and tightness in the leg muscles are common causes of knee pain. By stretching and strengthening the knee muscles, you can reduce the forces going through the joint, reducing pain and swelling, and improving function.
You can find out all about the different muscles in knee joint anatomy, how they work, how they can get damaged and how to strengthen and stretch them in the knee muscles section.
In knee joint anatomy, knee ligaments are the main stabilising structures of the knee preventing excessive movements and instability. Ligaments are tough, fibrous connective tissues which link bone to bone, made of collagen.
There are two sets of knee ligaments:
In the knee ligaments section we look at each of the different ligament in-depth including how they work, what their role is, how they get damaged and how to make the best recovery from ligament injuries.
Tendons are often overlooked as part of knee joint anatomy. They are they soft tissues found at the end of muscles which link the muscle to bone.
The main tendon found at the knee is the patellar tendon which links the quads muscles to the shin bone. The knee cap actually sits inside the patellar tendon.
Tendons are frequently damaged by overuse or excessive stretching resulting in tendonitis. The most common knee tendonitis problem is patellar tendonitis (aka Jumpers Knee) at the front of the knee.
Now let's have a look at knee bursa anatomy. There are approximately fourteen bursa around the knee.
Bursa are small fluid filled sacs that reduce the friction between the bones and soft tissues to prevent inflammation.
If there is excessive friction on the bursa, usually due to muscle weakness, tightness or repetitive pressure, then the bursa gets inflamed, known as knee bursitis.
In the knee bursa section we look at each of the bursa, where they are, what they do, how they get injured and how to make a full recover from bursitis.
Another important part of knee anatomy is the joint capsule. This is like a bag that surrounds the joint containing synovial fluid to nourish and lubricate the knee allowing it to move smoothly and freely.
Any swelling that occurs in the joint is contained inside the capsule, which is why injuries can cause the knee to "balloon". If the joint capsule is damaged, swelling is no longer confined to the joint so tends to actually be less obvious.
You can find out more in the knee swelling section.
When looking at the anterior aspect of knee joint anatomy, you will find the patella (kneecap).
The patella is a small, triangular bone which sits in the quadriceps muscle at the front of the knee.
The kneecap is lined with cartilage which is actually the thickest cartilage in the whole body due to the massive forces that go through it e.g. the force going through the kneecap when coming downstairs is 3.5x body weight.
Knee cap pain is one of the most common problems associated with the knee.
The specific design of knee joint anatomy allows a number of functions:
Alternatively, if you have a knee problem and want help working out what is wrong, visit the diagnosis section.
Page Last Updated: 22/01/20
Next Review Due: 22/01/22