In Depth: Deep Muscles
The muscles of the lower back help stabilize, rotate, flex, and extend the spinal column, a bony system comprised of 24 vertebrae that gives the body structure and houses the spinal cord. The spinal cord and its nerves are the means by which the body and brain communicate. Together, the brain and spinal cord make up the central nervous system.
The multifidus is a long muscle that travels nearly the entire length of the back. It stabilizes and rotates the lumbar spine. One important physiologic function of this muscle is to take pressure off vertebral discs and create padding between vertebrae so the body’s weight can be evenly distributed.
The multifidus starts at the base of the spine at the sacrum and extends up the second vertebra in the neck. The muscle features multiple insertion points along the spine, specifically into the spinous process of each vertebra. The spinous process is the protrusion of the bone than can be felt through the skin.
It can be felt through the skin to the immediate left and right of the vertebrae.
The multifidus and other muscles connect to the vertebrae and bones via ligaments, which are flexible bands of fibrous tissue. The deep muscles of the back, including the multifidus, fit into or affix parts of themselves to the grooves in the spinous process.