Medial collateral ligament bursa

Line drawing represents axial section of medial side of knee. Note three distinct layers (I, II, and III). Layer I corresponds to crural fascia, layer II contains superficial portion of the medial collateral ligament (also referred to as the tibial collateral ligament), and layer III contains deep portion of the MCL. The MCL bursa (B) is located between superficial and deep portion of the MCL. Also note split in layer II along anterior margin of superficial MCL (arrowheads). Anteriorly, layer I is fused with layer II (curved arrow), whereas posteriorly, layer II joins layer III (short arrows). Sartorius tendon is embedded in layer I (S).