The medial collateral ligament (MCL) of the knee is a flat, triangular band on its medial aspect that resists valgus forces. It forms part of the medial capsuloligamentous complex of the knee.
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Gross anatomy
The medial collateral ligament measures 8-10 cm in length and has superficial and deep portions 4. The superficial component is important for knee stability when valgus forces are applied.
Superficial MCL
The superficial MCL, also known as a tibial collateral ligament or vertical component of the MCL, is part of the middle layer of the medial capsuloligamentous complex of the knee. Its proximal attachment is the posterosuperior aspect of the medial femoral epicondyle, anteroinferior to the adductor tubercle. Distally it has two insertion sites (proxima and distal) at the upper medial surface of the tibia 1-5:
anterior band of the semimembranosus tendon (principally a soft tissue attachment)
tibial periosteum posterior to the pes anserine attachment at the posteromedial crest of the tibia
The posterior aspect of the medial collateral ligament blends into the posterior oblique ligament and knee capsule.
Deep MCL
The deep MCL, also known as the mid-third capsular ligament, is part of the deep layer of the medial capsuloligamentous complex of the knee, and is a thickening of the medial joint capsule, and is divided into meniscofemoral and meniscotibial ligaments 4,5.
Arterial supply
branches of the superior and inferior genicular arteries 5
Innervation
medial articular nerve, a branch of the saphenous nerve 5