The spinal column is a bony tower of 24 vertebrae that gives the body structure, while also housing the spinal cord. The spinal cord and its nerves are the means by which the body and brain communicate with one another.

Four distinct but adjacent sections make up the spinal column: the cervical (neck), thoracic (abdomen,) lumbar (lower back), and sacral (toward tailbone) spine. The lumbar spine is located in the lower back and typically consists of five vertebrae. The muscles of the lower back help stabilize, rotate, flex, and extend the spinal column.

Deep muscles of the lower back include:

  • The multifidus, a long muscle that travels nearly the entire length of the back. It helps to stabilize and rotate the lower back, and additionally takes some of the pressure off the inter-vertebral discs.
  • The iliocostalis lumborum, the lumbar portion of the iliocostalis muscle. This muscle attaches to the iliac crest of the upper pelvis and the posterior ribs at the back of the body. It is responsible for the primary movement of back extension and helps ensure correct posture.
  • The longissimus, a muscle that begins in the middle of the lumbar spine and continues up to the articular processes of the cervical vertebrae. This muscle blends with the iliocostallis lumborum in the lumbar region and assists with back extension.