fibular collateral ligament

People who specialize in medicine have a better understanding of various parts of the body and are very clear about the structure of each part of the body. Because in medicine, only by distinguishing the specific parts can we accurately find out where the disease is. The anterior collateral ligament is a ligament located in the knee joint. There are many ligaments in the knee joint, and the anterior collateral ligament is just one of them. Let’s learn about the functions of the anterior collateral ligament.

1. Fibular collateral ligament

The fibular collateral ligament is a ligament of the knee joint. This ligament is a cord-like, tough fiber that is located on the outside of the joint. It starts from the lateral epicondyle of the femur and ends at the middle part of the lateral surface of the head of the fibula. There is loose connective tissue between this ligament and the joint capsule, and it is separated from the meniscus by the popliteus tendon. The two are not directly connected. When the knee is flexed and the calf is internally rotated, both the tibial and fibular collateral ligaments relax. On the contrary, it is tense when the knee is extended and the calf is externally rotated, thus limiting excessive extension and external rotation of the knee joint.

2. Physiological significance of the fibular collateral ligament

The fibular collateral ligament and the tibial collateral ligament have the function of reinforcing the knee joint from both sides. When the knee is flexed and internally rotated, the fibular collateral ligaments relax, allowing the lower leg to rotate at the knee in a small range of motion; when the knee is extended, they tighten, preventing excessive extension and external rotation of the femur.

When the fibular collateral ligament is loose, the violent impact of excessive adduction (varus) on both sides of the knee joint may cause injury to the fibular collateral ligament.

The peroneal collateral ligament can be considered as the upward extension of the peroneus longus. The fibular collateral ligament is divided into two parts. The fibular collateral ligament usually refers to its superficial part, and its deep part was formerly called the external short ligament. In its occurrence, due to the inconsistent growth rates of the tibia and fibula, the upper part of the fibula is lower than the tibial articular surface, and the tip of the fibula forms an extension of the original part of the joint capsule. Therefore, there is a part of the posterior and outer edge of the upper end of the tibia without joint capsule attachment, and is replaced by the popliteus tendon. The extended part of the joint capsule that is pulled down is the deep part of the fibular collateral ligament. Unlike the tibial collateral ligament, the fibular collateral ligament is directly connected to the lower part of the lateral meniscus. The popliteus tendon is between the lateral meniscus and the deep part of the ligament, and it is surrounded by a synovial sheath, forming an oblique groove behind the outer edge of the lateral meniscus. The tibiofibular collateral ligaments are located to the back of the knee joint. When the knee is flexed, the collateral ligaments are relaxed and the tibia can rotate slightly to control abduction, adduction or rotation. When the knee is extended, the collateral ligaments are tense and the knee joint becomes stable, which can prevent the knee from overextending. When the calf is externally rotated, the fibular collateral ligament is relaxed and sometimes twisted, curled and protruded.