The knee joint is a complex structure that is made up of several bones. These bones work together to allow the knee to bend and straighten.

In this blog post, we will take a detailed look at the anatomy of the knee joint. This includes discussing what bones make up the knee joint.

If you are interested in learning more about the anatomy of the knee joint, then this blog post is for you!

The Knee Joint


The knee, or tibiofemoral joint, is the largest joint in the human body. The knee is a hinge joint, meaning it can bend and straighten like a door hinge. This complex joint has three main knee bones and various muscles, tendons, and ligaments that keep it stable and allow us to walk, run, and jump.

What Bones Make Up the Knee Joint?

The knee joint consists of three bones. They are all crucial to the integrity and function of the knee joint.



The femur (thigh bone) is the bone that connects the hip to the knee. It is also the largest bone in the body and provides structural support for our legs. It is a major attachment site for many thigh muscles and other musculature necessary for daily or athletic movement.



The tibia (shin bone) is located between the knee joint and ankle joint. It is the lower legs’ weight-bearing bone when we walk, run, or jump. It also works with muscles and tendons to keep the knee joint stable.



The patella (kneecap) is a small, triangular bone located at the front of the knee. It functions as a shield for the joint, protecting it from impacts and abrasions during activities such as running or jumping. It also works with muscles and tendons to help the knee move properly.

The Joint Capsule

In the joint capsule, there is synovial fluid and a synovial membrane that helps to lubricate the joint as we move. It also helps provide cushioning when our knee flexes, extends or rotates.

Covering the ends of each of the previously mentioned long bones (tibia and femur) there is articular cartilage that helps smooth out movements and prevent degradation to the ends of the bones.

There is also a meniscus which consists of two C-shaped pieces of cartilage. The medial meniscus and the lateral meniscus, each act as a shock absorber and sit between the articulating surfaces, helping to stabilize the knee joint.

Ligaments of the Knee Joint

Besides the meniscus, other soft tissues support the knee joint. Namely, the ligaments. The two main types of ligaments that support the knee joint are the cruciate and collateral ligaments.

The cruciate ligaments are located inside the knee joint and help to provide stability when we move. The two cruciate ligaments, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) work together with muscles to provide support and control the back-and-forth movement of the knee.

The collateral ligaments are on the sides of the knee joint and help provide stability when we move from side to side. The medial collateral ligament (MCL) is located on the inner part of the knee and helps keep it stable when we turn or twist our knees.

The lateral collateral ligament (LCL) is located on the knee’s outer part and helps keep our knees stable while we move.

Muscles of the Knee Joint

The knee is also supported by several muscle groups, namely the hamstrings, calves, and quadriceps muscle groups. Each muscle group has its function and helps to keep the knee moving properly.

The hamstring muscles are located at the back of the thigh and help bend the knee. This muscle group is comprised of the semitendinosus, semimembranosus, and biceps femoris muscles.

The calves, located on the posterior lower leg, help us to stand on our toes via plantarflexion. The muscle group is comprised of the gastrocnemius, soleus, and plantaris muscles.

The quadriceps are located on the front of the thigh and help us to extend our legs. This muscle group is made up of four muscles: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

On the front of the knee, there is also the quadriceps tendon and patellar tendon. The job of these tendons is to help connect the quadriceps muscle group to the patella or lower leg and help with knee extension.

Both the front and back of the knee are protected by various musculature to help keep the knee joint healthy and free of injury.

Common Knee Injuries

The knee joint is a delicate structure and can easily be injured. Some of the most common injuries include:

  • Tendonitis: Tendonitis is a condition in which the tendons become swollen, inflamed, and painful. This is caused by overuse or repetitive use of the knee joint.
  • Ligament Sprains or Tears: Sprains occur when a ligament is stretched beyond its limits, sometimes potentially tearing. This can happen during activities like contact sports or other physical activities that involve sudden changes in direction or twisting motions.
  • Meniscus Injuries: A meniscal tear can occur when the knee joint is suddenly flexed or twisted. This causes a tear in the meniscus, which can be painful and cause swelling.
  • Arthritis: Arthritis is a condition that causes inflammation of the joints and can make movement difficult. Knee osteoarthritis is one common type of arthritis that can cause pain, stiffness, and swelling.

Overall, the knee joint is a complex structure, and understanding how it works and what can cause injury can help protect it from damage. It is important to learn proper techniques for using the joint as well as how to recognize when an injury might be occurring.

Taking steps to keep your knee healthy will help ensure that you can continue with all of the activities you enjoy. Regular exercise, stretching, and proper nutrition can all help to keep your knee joint strong and healthy.

Additionally, it is important to wear proper footwear and protective gear when participating in physical activities that involve the knee.

By taking care of your knee joint, you can ensure that it will continue to provide you with mobility and support for many years to come.

About the Author

Hi there! I’m Dr. Keagen Hadley, OTD, OTR/L. Straight out of the University of Mary, I’m all about blending my know-how in knee health, well-being, and medical technology. As a licensed occupational therapy doc, I’m here to translate complex concepts into clear, actionable insights – whether it’s knee care or groundbreaking healthcare tech.

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