Ligaments are tough bands of fibrous tissue that connect bone with bone and provide stability to the joints. There are four ligaments involved in the knee joint. Two ligaments are present inside the knee joint (CRUCIATE LIGAMENTS) and two ligaments are present on the outside (COLLATERAL LIGAMENTS). One ligament that connects the Patella (Knee Cap) to Femur (thigh Bone) is called Medial Patelo-Femoral Ligament (MPFL).
Cruciate Ligaments (also cruciform ligaments) are pairs of ligaments arranged like the letter X.
Collateral Ligaments and Posterolateral Complex
The collateral ligaments are extra-articular (outside the knee joint). The medial collateral ligament is present on the inner side and lateral collateral ligament is a part of the Postero-Lateral Complex (PLC) which is present on the outer side of the knee.
Structures found in the posterolateral knee include Tibia, Fibula, Lateral Femur, Iliotibial Band (IT band), the long and short heads of the Bicepsfemoris Tendon, Fibular (lateral) Collateral Ligament (FCL), Popliteus Tendon, Popliteofibular ligament, Lateral Gastrocnemius Tendon, and Fabellofibular Ligament.