Knee joint capsule
The knee joint capsule allows the full knee to have flexion, or bending, motion due to the folds in the capsule. The joint capsule is made up of the patella, which is within the anterior capsule, as well as the tibia and the femur. The patella is also known as the kneecap. The capsule is held together with ligaments that help with the range of motion. The capsule has synovial fluid, or fluid found in the cavities of synovial joints, that will circulate around the patella, tibia, and femur. Its posterior aspect, or back part of the structure, is stronger and thicker. It makes the person, when standing, more stable and able to balance. The knee joint capsule provides static stabilization for the knee, which is unstable due to its bony configuration. The knee joint itself has two nearly flat surface bones. These surface bones lie on one another as a primary articulating surface. It is the capsule that provides the knee joint its movement.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Knee joint capsule