The knee is the largest joint in the human body and one of the most complex.
It also supports many stresses, so its design to give functionality in mobility and stability is truly exceptional. Without the knee it would be difficult to get up or walk, and almost impossible to run as human physioanatomy is understood.
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What is the knee?
The knee is the joint that links the thigh to the calf. It is thus located in the center of the leg, and has functions such as allowing it to bend or rotate.
The anatomy of the knee joint comprises different structures in and around the knee. Several muscles control movement, and tendons transmit it to the bones.
On the other hand, ligaments provide stability, and cartilage absorbs pressure exerted on the joint. Other structures also guarantee a smooth movement that does not cause injury or pain, although the wear and tear to which it is subjected over the years can generate different types of problems.
Many of the soft structures have the function of preventing friction and protecting the joint. Any damage could generate different types of injuries, seriously affecting the viability of the joint itself.
Knee joint: tendons, muscles, ligaments and other structures
The anatomy of the knee is a joint consisting of many structures. Bones, tendons, muscles and ligaments are some of the most important, but not the only ones.
Each and every one of them is fundamental so that the functions of the articulation can be carried out. Below are what they are starting with the bones, which make up the structural base.
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1. Bones
Bones may represent the most recognizable part of the knee. The bony structures of this joint are the femur, tibia and patella, the latter being a bone exclusively designed for the knee joint.
The kneecap is a circular and flat bone that is located in the front of the knee. It plays a fundamental role for the extension of the leg with the help of other soft structures that are presented below, and also protects the ends of the femur and tibia.
2. Ligaments
Ligaments are structures that connect bones to each other. In the knee there are four main ligaments: posterior cruciate ligament, anterior cruciate ligament, external lateral ligament and medial lateral ligament.
Each of them gives stability to the knee, avoiding lateral displacement and supporting the tension generated by the rotation of the tibia. It is therefore a very important structure to avoid the dislocation of the joint, something that if not for the ligaments could occur during movement.
3. Articular cartilage
Cartilage is a structure that protects bones and gives fluidity to movement. They are one of two types of cartilage that can be found in the knee, and represent the lining that covers the ends of the bones that form the joint.
The articular cartilage is soft and smooth, and prevents the bony part of the structure from being exposed. When it wears irremediably, damage occurs in the knee joint, this being the cause of the appearance of arthritis.
4. Menisci
The other cartilaginous structures of the knee are the two menisci. These are called lateral or external meniscus and medial or internal meniscus, and their main function is cushioning, although they also participate in facilitating movement.
They are located between the femur and tibia, which allows the two bones to be mobile structures without suffering irreversible damage. This soft structure is essential so that internal injuries do not occur from trauma or any type of damage caused by friction.
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5. Tendons
Tendons are responsible for connecting muscles to bones . If the muscle receives the signal to contract, it does so by pulling on the tendons, which in turn causes the bones to move.
One of the most important tendons is the patellar or patellar tendon. This fibrous structure is one of the thickest tendons in the body, and has attachments to the patella and tibia. However, the tendons that surround the knee joint are different.
6. Muscles
Different muscles have the function of driving the knee forward and backward . Of all of them, two muscle groups stand out significantly: the quadriceps muscles and the hamstring muscles.
The quadriceps muscles are responsible for providing the strength and power associated with leg extension. On the other hand, the hamstring muscles do the same with the flexion of this limb.
7. Joint capsule
The joint capsule is a fibrous structure that protects the different tissues . This layer covers the joint with the two menisci, the collateral ligaments, and the cruciate ligaments.
The joint capsule is intimately linked to the other tissues of the knee. For this reason, any swelling that occurs in the knee is also manifested in the synovial capsule, which can lead to generalized inflammation of the joint.
8. Synovial bursa
The synovial bag or bursa lines the inner surface of the capsule . It is actually different small sacs that contain a very important viscous fluid called synovial fluid. This lubricates and nourishes the joint, being essential for the functioning of the entire structure.
In addition, the synovial fluid allows to avoid friction between the different structures when they are performing their mechanical work. This is very important so that the conditions of the bones and other soft tissues are optimal. When there is excessive tension or pressure, the bursa becomes inflamed and an injury known as bursitis occurs.
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Bibliographic references
- Flandry, F., Hommel G. (2011). Normal anatomy and biomechanics of the knee. Sports Med Arthrosc Rev., 19 (2), 82-92.
- Moore, K.L., Dalley, A.F. y Agur, A.M.R. (2006). Clinically Oriented Anatomy. Lippincott Williams & Wilkins.
- Scott, J., Lee, H., Barsoum, W. y Van Den Bogert, A.J. (2007). The effect of tibiofemoral loading on proximal tibiofibular joint motion. Journal of Anatomy, 211 (5), 647–653.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.