Lateral meniscus

At a glance

English

Lateral meniscus

Latin (TA2)

Meniscus lateralis

System

Cartilage

Region

Lower limb

Side

Paired, left and right

About the lateral meniscus

The lateral meniscus is the outer of the two crescents of fibrocartilage inside the knee joint. It sits on the lateral condyle of the tibia and cups the lateral condyle of the femur above. Compared with the medial meniscus it is almost a closed ring, of nearly even width all round, and it covers a larger share of the tibial surface it rests on. In section it is a wedge, thick at the capsular edge and sharp at the free inner border.

Its two horns are attached close together on the intercondylar area of the tibia. The anterior horn is fixed in front of the intercondylar eminence, behind and lateral to the anterior cruciate ligament and partly blended with it; this end is twisted so that its free margin faces backwards and upwards where it lies on a slanting ledge of bone. The posterior horn is fixed behind the eminence, in front of the posterior horn of the medial meniscus. Near this posterior attachment a stout band, the posterior meniscofemoral ligament (of Wrisberg), runs upwards and medially to the femur's medial condyle behind the posterior cruciate ligament; a matching anterior band (of Humphrey) may pass in front of that ligament. The transverse ligament of the knee joins its front margin to the medial meniscus.

On its outer side the meniscus is grooved by the tendon of popliteus, which runs between it and the fibular collateral ligament. Because of this the lateral meniscus is not attached to the collateral ligament, and popliteus, which has fibres inserting into it, pulls its back part out of the way when the knee unlocks. It is therefore much more mobile than the medial meniscus and slides across the tibial condyle during rotation.

The meniscus deepens the shallow tibial surface, spreads load from the femur, absorbs shock and helps lubricate and steady the joint. Its greater mobility makes it less often torn than the medial meniscus, though twisting and contact sports can still tear it. Swelling and stiffness follow a tear, and McMurray's test helps detect it. Small tears can settle with rest, ice, pain relief and graded exercise; larger ones are repaired or trimmed by arthroscopy. A discoid meniscus, a disc-shaped variant, is found almost only on this side.

Attachments and function

Attaches from

Anterior horn on the anterior intercondylar area of the tibia, behind and lateral to the anterior cruciate ligament.

Attaches to

Posterior horn on the posterior intercondylar area, in front of the medial meniscus; it is also tied to the medial femoral condyle by the meniscofemoral ligaments.

Function

Deepens the lateral tibial condyle, spreads load, absorbs shock and stabilises the lateral compartment while gliding during rotation.

Nerve supply

Its outer part receives twigs from the genicular branches of the common fibular, tibial and obturator nerves.

Blood supply

The outer third is supplied by the lateral and middle genicular arteries through a perimeniscal plexus; the inner part depends on synovial fluid.