Medial meniscus

The medial meniscus is a C-shaped fibrocartilaginous structure located on the medial side of the knee joint, interposed between the medial femoral condyle and the medial tibial plateau. It is wider posteriorly than anteriorly and covers approximately 50% of the medial tibial plateau surface area.

The medial meniscus is anchored to the tibia at its anterior and posterior roots, with the anterior root attaching to the anterior intercondylar area and the posterior root to the posterior intercondylar area of the tibia.

The meniscus is divided into zones based on its attachments: the anterior root (zone 1), anteromedial (anterior horn; zone 2), medial (body of meniscus, zone 3), posterior (posterior horn; zone 4), and posterior root (zone 5).

The peripheral border of the medial meniscus is attached to the joint capsule via the meniscocapsular ligament, while the posteroinferior edge is anchored by the meniscotibial ligament. The posterior horn is closely associated with the semimembranosus tendon, which has a capsular branch inserting behind the meniscus and contributes to its dynamic stability.

Vascular supply is greatest in the peripheral (outer) third, with the inner two-thirds being relatively avascular and composed mainly of dense extracellular matrix proteins such as collagen type II and aggrecan.

The medial meniscus is less mobile than the lateral meniscus due to its firm capsular and ligamentous attachments, making it more susceptible to injury.