Structure
The medial meniscus of the knee joint is a flat, intra-articular, semicircular fibrocartilaginous band. It is attached to the anterior intercondylar area of the tibia via its anterior horn, anterior to the attachment of the anterior cruciate ligament. The posterior horn is attached to the posterior intercondylar area of the tibia, between the attachment sites of the posterior cruciate ligament and the posterior horn of the lateral meniscus.
The outer attached borders of the menisci are thick and convex, while the free, inner borders are thin and concave. The outer margins are vascularized, while the inner free margins are avascular. Thus, peripheral tears are more likely to heal compared to tears on the inner margins. The horns of menisci are richly innervated, while the central parts are devoid of innervation.
The anterior horn of the medial meniscus is attached anteriorly to the transverse ligament of the knee. The peripheral border has additional attachments to the fibrous capsule and the inner surface of the medial collateral ligament.
Related parts of the anatomy
Anatomical Relations
The anterior horn of the medial meniscus lies in front of both the anterior cruciate ligament and the intercondylar eminence. The posterior horn lies behind the intercondylar eminence, where it is fixed between the attachments of the posterior horn of the lateral meniscus (anteriorly) and the posterior cruciate ligament (posteriorly).
Function
The menisci of the knee joint function to widen and deepen the tibial articular surfaces that receive the femoral condyles, providing stability to the knee joint.
Both the lateral and medial menisci slide backwards with flexion and forwards in extension at the knee joint and act as shock absorbers in the knee joint. The menisci can be injured or torn by twisting the knee or applying direct force to them, as seen in contact sports. The lateral meniscus moves more compared to the medial meniscus, and hence is less prone to injury compared to the medial meniscus. The latter is denied free mobilization because of its additional attachments to the fibrous capsule and the medial collateral ligament.
List of Clinical Correlates
—Meniscal tears
—Unhappy triad
