sentences: the parts point knee onto the ground
docs: ground is military_position. right_knee_joint is knee. right_kneecap is kneecap. knee is external_anatomical_part. right_knee_joint is knee_joint. heel_of_hand is physical_surface. left_knee_joint is knee_joint. kneecap is knee. knee is part_of_leg. left_knee_joint is knee.