n.屈肌
As flexor control is stimulated, the child will actively lift the pelvis. 当屈肌的控制被激发以后，儿童就会积极地抬起骨盆。
If there is any need to strengthen the muscles, it is the hip flexor. 如果有任何肌肉需要强化，那就是臀部屈肌。
