Fig. 2.

Enlarged view of Figure 1, showing the origin and insertion of the articularis genus. The bundles of the superficial layer (indicated by the number 1) and, in 60% of the specimens, the bundles of the intermediate layer (indicated by the number 2) originated from both the deep surface of the vastus intermedius (VI) aponeurosis and from the anterior and anterolateral surfaces of the femur. The bundles of the deep layer (indicated by the number 3) and, in 40% of the specimens, the bundles of the intermediate layer originated entirely from the anterior surface of the femur. Distally, the articularis genus bundles inserted gradually into the suprapatellar bursa and the joint capsule (asterisks), with the bundles of the superficial layer inserting into the synovial membrane adjacent to the quadriceps tendon (red asterisk), the bundles of the intermediate layer inserting into the middle section of the suprapatellar bursa (orange asterisks), and the bundles of the deep layer inserting into the synovial membrane facing the femur (yellow asterisk). Proximally, no distinct investing fascia separated the articularis genus from the vastus intermedius; in that area, the articularis genus muscle bundles were in continuity with the deep muscle fibers of the vastus intermedius (white asterisks). Distally, the deep and intermediate articularis genus muscle bundles were partially separated by or imbedded in a considerable amount of fatty tissue (orange arrow). For better visualization of the articularis genus muscle bundles, the fatty tissue was partially removed. VM = vastus medialis. P = Patella.