Muscles That Act on the Spine

The lower back is also significantly influenced by three sets of muscles that attach to the pelvis or the lumbar vertbrae: the hip flexors (which raise the thigh toward the chest)(即：髖骨前的一組深層肌肉), the abdominals, and the hamstrings (the long muscles on the back of the thigh). By altering the forward or backward tilt of the pelvis, these muscles can increase or decrease the lumbar curve. For example, because the hip flexors attach to the front of the pelvis, tight hip flexors will tilt the pelvis forward, creating a swayback. Tight hamstrings will tilt the pelvis backward, creating a flat back. Weak abdominal muscles will allow the pelvis to drop forward and will fail to support the lumbar spine from the front.

P.15, Back Care Basics, Mary Pullig Schatz, M.D.