Deep part of tibial collateral ligament

At a glance

English

Deep part of tibial collateral ligament

Latin (TA2)

Pars profunda ligamenti collateralis tibialis

System

Ligament

Region

Lower limb

Side

Paired, left and right

About the deep part of tibial collateral ligament

The tibial (medial) collateral ligament of the knee has two layers. The deep part is the inner one: a short, thick band that is really a strengthened portion of the joint capsule on the medial side. It lies directly under the long superficial part, from which it is separated by a thin bursa that lets the two layers slide on each other.

The deep part runs from the femur just below the medial epicondyle to the tibia just below its articular margin, so it spans the joint line only briefly. Its key feature is its firm union with the outer edge of the medial meniscus. The fibres above the meniscus form a meniscofemoral portion, and those below, which tie the meniscus to the tibia, form a meniscotibial (coronary) portion. This binding is one reason the medial meniscus is far less mobile than the lateral meniscus.

The deep part is a secondary restraint against valgus force, the force that pushes the knee inwards and opens the medial side of the joint. It also helps to limit rotation and anchors the meniscus as the knee moves. Evolutionarily, the whole medial collateral ligament represents the lost lower end of the adductor magnus tendon, which in many animals runs on to the tibia; for this reason the ligament occasionally contains a few muscle fibres.

Medial collateral injuries arise when the partly flexed knee is forced into valgus, as in skiing falls, tackles or awkward landings, or from a blow to the outer side of the knee. Because the deep part is attached to the meniscus, a tear may come with a meniscal injury, and with the anterior cruciate ligament in more severe twisting. Injuries are graded from a sprain to a complete tear; most are treated without surgery using a brace and rehabilitation, while unstable high-grade tears may be repaired or reconstructed.

Attachments and function

Attaches from

The medial femoral condyle just below the medial epicondyle.

Attaches to

The medial tibial condyle just below the articular margin, with firm attachment to the medial meniscus in between.

Function

Acts as a secondary restraint against valgus and rotational stress and anchors the medial meniscus to femur and tibia.

Nerve supply

Articular branches of the saphenous nerve and of the obturator nerve to the inner knee.

Blood supply

The superior and inferior medial genicular arteries.