What is the knee?
The knee is one of the most resistant joints in the human body. It is sufficiently mobile and allows movement of the lower part of the leg, which helps carry out daily activities such as walking, sitting, running and maintaining an upright position. The knee is also plays an essential role in supporting body weight.
The knee joint is formed by a group of three bones: the femur , tibia and patella. The femur and tibia are connected at their ends, while the patella (kneecap) is situated in front of the femur. The joint surfaces are coated by a thin layer of cartilage which protects the bones and helps them slide easily over each other, averting dangerous friction during movement. Between the femur and tibia there is another fibrocartilaginous structure known as the meniscus. It protects the ends of the bones by preventing contact among them during strenuous activities such as running and jumping. Finally, the bones of the knee are surrounded by a capsule that has a synovial and a fibrous membrane, responsible for lubrication of the joint. The capsule is in direct contact with the ligaments that hold the knee in place, help strengthen the structure and ensure proper positioning of the bones.
The patella is held in place by the patellar ligament, which extends from its lower edge up to the tibia. At the rear, the obique popliteal ligament and the arcuate popliteal ligament join the femur to the tibia and fibula. The lateral collateral ligament and the medial collateral ligament connect with the femur and tibia, and help prevent the knee from moving sideways towards the inside or the outside of the body. Lastly, the anterior cruciate ligament prevents excessive extension of the knee and averts the femur from sliding backwards on the tibia, while the posterior cruciate ligament prevents the femur from sliding forward on the tibia.
Other structures that help protect the knee joint from external forces and frictions include numerous sacs containing a liquid lubricant, as well as the formation of adipose tissue, which helps reduce friction between the bones and acts as a buffer in order to absorb external forces.
Conditions associated with the knee may include injuries, arthritis, patellofemoral syndrome and others. Knee pain is generally caused by trauma, misalignment and degeneration. A majority of cases can be treated at home however more severe injuries may require immediate medical attention in order to prevent further complications from arising.
What function does the knee serve?
The knee permits flexion and extension of the lower leg with respect to the thigh. Its range of movement is restricted by its anatomy and stops about 120 degrees, however, in comparison with other joints; it is moderately flexible and allows a certain internal and external rotation. Unlike the hip joint, which is partly protected by bony structures of the pelvis, the knee joint is not protected by any other parts of the skeleton. The ligaments surrounding the knee provide the main stability. Additionally, the knee joint bears the weight of the upper body and absorbs the shock carried upward through the feet during vigorous activities such as running or jumping.
