Being the largest and perhaps most complex joint in the body, the knee joint has five major ligaments (fibrous connective tissue) that reinforce its stability. Included among them is the patellar ligament, the tendon largely responsible for knee extension.
The lateral patellar ligament, along with its medial counterpart, is a part of the patellar ligament. These two ligaments are very soft and tender.
These ligaments belong to the external ligaments because they run outside the capsule of the kneecap, or patella, which has three areas: base, apex, and posterior surface. The patellar ligament is situated in the apex area.
The lateral patellar ligament is also where the vastus lateralis muscle is inserted. This muscle is one of the muscles in the anterior (front) and medial (middle) thigh, the main function of which is to extend the leg.