The anatomy of the knee joint (Sinelnikov R. D. and other authors consider it in sufficient detail) is quite complicated. This joint in the human body consists of many parts. The connection takes on the most difficult loads, distributing the weight several times higher than its own. The complexity of the joint is due to its components. These are the largest bones of the lower extremities.
3 bones are involved in the formation of the joint. They are connected by a powerful articular apparatus, which includes a joint capsule, ligaments and synovial bags. The entire joint is driven by the muscles of the legs.
The structure of the knee
The knee consists of three bones, the muscles that provide its movement, nerve endings and blood vessels, menisci, cruciate ligaments. Such a complex structure is caused by high loads. Anatomy of the knee joint provides maximum comfort when moving on 2 limbs. In primates, the structure is much simpler due to the presence of 4 limbs.
The surface of the femur (condyles) has the shape of an ellipsoid. The medial condyle has a greater curvature than the lateral condyle. Between the condyles there is a patella surface. It is located in front of the femur and is divided by a vertical groove into a smaller inner and larger outer sections. They are connected to the posterior articular surfaces of the patella.
The surfaces of the condyles are slightly concave and do not correspond to the bends and curvatures of the femoral condyles. Despite this discrepancy, inter-articular cartilage (internal and external menisci) align it.
Functions and Movement
The knee joint can perform the following movements: flexion, extension and rotation. The nature of the joint is condylar. When unbent, the menisci are compressed; when bent, they are unclenched. Due to the fact that the collateral ligaments are relaxed in this position, and their attachment points are as close to each other as possible, there is the possibility of movement - rotation.
When the lower leg rotates inward, the movement is limited by the cruciate ligaments, when moving outward, they relax, and the amplitude is limited already by the lateral ones.
Menisci
The anatomy of the knee joint has been studying the structure and function of menisci for many years, since the injuries associated with them are a very common occurrence.
Menisci are trihedral cartilaginous plates thickened on the outside (fused with the joint capsule), inside facing the joint and pointed. Above they are concave, flattened from below. From the outer edges repeat the anatomy of the upper edges of the condyles of the tibia.
The lateral meniscus is similar in shape to a part of the circle, while the medial meniscus resembles a lunar shape.
The cartilaginous plates are attached in front (using the transverse ligament of the knee) and back to the tibia (intercondylar eminence).
Key ligaments
The brief anatomy of the knee always describes the cruciate ligaments (front and back) that are located directly in the knee. They are called intracapsular ligaments.
In addition to them, the joint has lateral collateral (medial and lateral). They are also called extracapsular ligaments, since they are located outside the joint capsule.
The extracapsular ligaments are represented by the tibial and peroneal collateral ligaments. They begin with the medial and lateral epicondyles of the femur and are attached to the superior epiphysis of the tibia and the outer surface of the fibula, respectively. Both connect to the joint capsule.
Intracapsular ligaments, anterior and posterior cruciate, begin on the inner surface of the lateral and medial condyle of the femur, go forward and inward (down and inward), are attached to the anterior and posterior tibial field, respectively.
Supporting ligaments
The topographic anatomy of the knee, in addition to intraarticular and extraarticular, also studies other ligaments.
The ligament of the patella is called the tendon 4-head of the thigh muscle, which goes from top to bottom, goes to the patella, grasps it from all sides and continues down to the tibia. Lateral tendon bundles go along the sides and go from the patella to the medial and lateral condyles of the tibia. They form the external and internal supporting ligaments of the patella.
In the supporting ligaments of the patella there are horizontal bundles that are attached to the epicondyle of the femur. The function of the supporting ligaments is to keep the patella in position.
Behind the joint capsule is strengthened by an oblique popliteal ligament. It starts from the condyle of the tibia and attaches to the condyle of the femur, giving part of the bundles to the joint capsule. The ligament takes part of the bundles from the tendon of the muscles of the thigh, namely from the semimembranous muscle.
The arched popliteal ligament is also involved in holding the patella. It starts from the femur and tibia, and is attached to the tibia. The ligament begins and ends on the lateral condyles.
The transverse ligament of the knee connects the menisci along their front surface.
The anterior meniscus ligament originates from the anterior part of the inner meniscus, follows up and outward, to the lateral condyle of the thigh.
The posterior meniscus ligament originates from the posterior edge of the external meniscus, follows up and inward, to the medial condyle of the thigh.
The condylar knee joint works as a block, being in an unbent position. Anatomy of the knee allows rotation along the vertical axis in a bent position.
Joint capsule
The joint capsule is attached to all three bones involved in joint formation.
To the femur, attachment occurs under the epicondyles, to the tibia - along the articular surface, to the patella - along its articular surface.
The synovial membrane covers the connecting surfaces of the bones to the cartilage and lines the cruciate ligaments. In addition to the smooth structure, the membrane forms many synovial villi and folds.
The most developed folds are pterygoid. They go along the sides of the patella up. And they contain a sub-patellar fatty body between their sheets.
The sub-patellar synovial fold lies below the bone itself, is a continuation of the pterygoid folds. It originates above the patella, goes into the joint cavity, is attached to the front edge of the fossa, between the condyles of the femur.
Synovial bags of the knee: anatomy and structure
The knee joint capsule forms several synovial bags. They can be located in various places of muscles and tendons, lying inside and between them. Synovial bags may be located among the bones and ligaments.
The tendon of the 4-headed thigh muscle and the anterior surface of the patella form a dry tendon pre-patellar sac.
The ligament of the patella and the tibia form a deep patellar synovial sac. Sometimes it has a connection with the cavity of the knee joint and is separated from it by a layer of adipose tissue.
These are the largest synovial bags of the knee joint.
Goose foot of the knee: anatomy and location
For the normal operation of the knee joint, there are a number of muscles that can be divided according to their location:
- The anterior thigh is the quadriceps.
- The back surface of the thigh is the biceps, semi-tendon, semi-membranous.
- The inner surface of the thigh is large, thin, long, short, adductors, and comb muscle.
On the lower leg there is a place where 3 thigh muscles are attached - tailoring, semi-tendonous and thin. In this place, the goose foot is formed, where the synovial bag is located.
Knee injuries
Knee injury is a very common occurrence. In order to diagnose the cause of joint pain, the doctor very often prescribes an MRI. The anatomy of the knee joint (bones, ligaments, muscles, arteries, etc.) is visible in the image, which will determine what is the cause of the discomfort.
Very often athletes, as well as those whose work is associated with physical labor, receive knee injuries. In order to reduce the risk of injury to the knee joint, it is necessary to regularly strengthen the muscles and ligaments. Perform simple exercises from articular gymnastics, regularly drink vitamin and mineral complexes. All these measures contribute to the strengthening of the knee joint and the muscles that set it in motion.