The medial meniscus is the "C" shaped fibrocartilage pad that helps transfer force from the tibia to the femur. Lay and sports people often use the term cartilage to mean the meniscal cartilage. Visit the "Learning About Your Knee" page on this site to learn of the difference between the meniscal cartilage and the articular cartilage. The second part of your question --medial--refers to the inner aspect of the knee. That is, if you put your knees together the areas touching are the medial aspects of both knees. The other meniscus is between the tibia and femur on the outside of the knee (lateral) and is called the lateral meniscus.