Anatomy Of The Knee

Anatomy of the Knee - joints

What’s In A Knee?

Your knee is a complex ‘hinge’ which effectively contains two separate joints.

There’s the main ‘hinge’ and a second joint between your knee cap and the front of the thigh bone. Because both parts are contained within a single capsule, any swelling in one affects both.

Your knees are made up of the following components:


  • The femur [thigh bone] is the largest bone in your body.
  • The tibia [shin bone] is the larger bone of the lower leg.
  • The fibula is the smaller bone in the lower leg, sitting on the outside of the tibia.
  • The patella [knee cap] sits in front of the femur and tibia and slides within its own groove on the femur as the knee moves.
Knee bones & ligaments
Ligaments - Anatomy of the knee


Ligaments connect the bones of the upper and lower leg. They are made of strong groups of fibres that help to provide stability to your knee.

There are two main groups of knee ligaments. They allow the joint to move, but they also prevent the joint from moving too much or abnormally.

Collateral ligaments:

  • The medial and lateral collateral ligaments [MCL and LCL] lie on the inner and outer sides of the knee respectively. They help to prevent sideways motion.

Cruciate ligaments:

  • The anterior cruciate ligament [ACL] and posterior cruciate ligament [PCL] lie in the centre of the knee crossing each other (hence “cruciate”). The ACL helps to limit rotation and forward motion of the tibia whilst the PCL located just behind the ACL limits the backward motion of the tibia.
  • In addition, there is a complex area called the posterolateral corner (PLC), which is made up of a group of linked ligaments, tendons and fibres that help keep things stable when you twist.

Muscles & Tendons

  • The quadriceps [‘quads’] are four muscles in front of the thigh that act to straighten the knee.
  • The hamstrings are the muscles in the back of the thigh that work together to bend the knee.

Tendons attach muscles to bones.

The four quadriceps muscles form into one tendon called ‘the quadriceps tendon’ which surrounds the patella and then becomes the patellar tendon as it attaches to the tibia below the knee.


Knee muscles & tendons
Cartilage - anatomy of the knee


Articular cartilage

  • The ends of each bone in your knee are covered with smooth cartilage. This ‘articluar’ cartilage reduces friction between the moving surfaces of the knee joint and helps to spread the loads that are applied to the joint. If you suffer from osteoarthritis, it’s this cartilage that will have worn away leaving bone to grind on bone. Find out more about arthritis and knee replacement.

Meniscal cartilage, meniscus

  • Between the femur and the tibia are two ‘C’ shaped wedges called menisci. These sit on either side of the joint and one of the functions is to act as shock absorbing cushions between the two main bones.

What is a torn cartilage?

  • When a meniscus is damaged, it is often referred to as a ‘torn cartilage’. This can be a confusing term, but when people talk about a torn cartilage, they usually mean the meniscus and not the articular cartilage.

Talk To The Knee Specialists In Yorkshire

If you are experiencing swelling, pain, locking or other knee conditions, talk to the orthopaedic specialists at Yorkshire Knee Clinic

To Book Your Appointment At Our Knee Injury Clinic

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