Soft tissues around the spine also play a key role in the health of the back. A large, complex group of muscles works together to support the spine and hold the body upright. They also allow the trunk of the body to move, twist and bend in many directions.

Three types of back muscles that help spinal function are the:

• Extensor muscles. Attached to the back of the spine, these muscles allow us to stand and lift objects. They include the large muscles in the lower back (erector spinae), which help hold up the spine, and gluteal muscles.
• Flexor muscles. Attached to the front of the spine, these muscles include the abdominal muscles. They allow us to flex, bend forward, lift and arch the lower back. When the abdominal muscles are weak, the muscles that allow us to bend at the hip get tighter, increasing the curve at the lower back.
• Oblique muscles. These are attached to the sides of the spine. They help us rotate the spine and maintain proper posture.
  

• The facet joints or other parts of the spine become injured and swell, which can cause the large muscles of the back to contract involuntarily (spasm)
• Chronic stress can causes the muscles to tighten up, using up energy that is needed to hold the spine upright
• Tight muscles in the back of the thighs can cause changes in the position of the pelvis, affecting spine movement