Thigh muscles, side view, artwork. Part of the pelvis is at top. At bottom are tendons (white) covering the kneecap (patella). At far left is the rectus femoris. It attaches to the pelvis, hip bone and patella and extends the knee and flexes the thigh at the hip. Immediately above the patella is the vastus medialis, which attaches to the thigh bone (femur) near the top and extends the knee. Above the vastus medialis is the iliacus, which attaches to the back of the pelvis and the top of the femur. It medially rotates the thigh and flexes it at the hip joint. At right is the adductor longus, which attaches to the pelvis and the mid femur. It flexes the thigh and laterally rotates the hip joint.