Anatomy of the muscles around the knee joint

The knee joint is an important node in the leg. It connects the thigh bone above and the tibia below, and is the core connection point for free movement of the leg. Although the knee joint is just a joint, its physiological structure is relatively complex and it is an important part of human physiology that cannot be ignored. The knee joint is relatively mobile, mainly due to the involvement of the surrounding muscle tissue. Let's take a look at the anatomical components of the muscles around the knee joint.

The knee joint is composed of the lower end of the femur, the upper end of the tibia and the patella. It is the largest and most complex joint in the human body and is a trochlear joint.

Anatomical structure: The patella is connected to the patellar surface of the femur, and the medial and lateral condyles of the femur are opposite to the medial and lateral condyles of the tibia respectively.

Main ligaments: The joint capsule of the knee joint is thin and loose, attached to the periphery of each joint surface, and reinforced with ligaments around it to increase the stability of the joint.

The main ligaments are:

1. Patellar ligament

It is the central fibrous cord of the quadriceps tendon, extending from the patella downward to the tibial tuberosity. The patellar ligament is flat and strong, and its superficial fibers pass over the patella to connect to the quadriceps tendon.

2. Peroneal collateral ligament

It is a tough, cord-like fibrous cord that starts from the lateral epicondyle of the femur and extends downward to the head of the fibula. Most of the ligament surface is covered by the biceps femoris tendon and is not directly connected to the lateral meniscus.

3. Tibial collateral ligament

It is wide and flat and is located on the inner and posterior part of the knee joint. It originates from the medial epicondyle of the femur, attaches downward to the medial condyle of the tibia and adjacent bones, and is tightly integrated with the joint capsule and medial meniscus. The tibial collateral ligament and the fibular collateral ligament are tight when the knee is extended, loose when the knee is flexed, and are most loose when the knee is half-flexed. Therefore, a small amount of internal and external rotation of the knee joint is allowed in the semi-flexed knee position.

4. Oblique ligament

It extends from the semimembranosus tendon, originates from the medial condyle of the tibia, slants upward and outward, and ends at the lateral epicondyle of the femur. Some fibers fuse with the joint capsule to prevent hyperextension of the knee joint.

5. Cruciate ligament of knee

Located slightly behind the center of the knee joint, it is very strong, lined with synovium, and can be divided into two front and back strips:

The anterior cruciate ligament originates from the inner side of the tibial intercondylar elevation, connects with the anterior horn of the lateral meniscus, and runs obliquely to the posterior, superior and lateral sides, with the fibers attached to the inner side of the lateral femoral condyle in a fan shape.

The posterior cruciate ligament is shorter, stronger, and more vertical than the anterior cruciate ligament. It originates from the posterior side of the intercondylar eminence of the tibia, moves obliquely forward and upward to the medial side, and attaches to the lateral side of the medial femoral condyle.