Muscle pain in the Lower back
The spine (spinal column) consists of back bones (vertebrae). The vertebrae are covered by a thin layer of cartilage and separated and cushioned by shock-absorbing disks made of jelly-like material and cartilage. They are held in place by ligaments and muscles, which include the following:
- Two iliopsoas muscles, which run along both sides of the spine
- Two erector spinae muscles, which run along the length of the spine behind it
- Many short paraspinal muscles, which run between the vertebrae
These muscles help stabilize the spine. The abdominal muscles, which run from the bottom of the rib cage to the pelvis, also help stabilize the spine by supporting the abdominal contents.
Enclosed in the spine is the spinal cord (see Spinal Cord and see Overview of Spinal Cord Disorders). Along the length of the spinal cord, the spinal nerves emerge through spaces between the vertebrae to connect with nerves throughout the body. The part of the spinal nerve nearest the spinal cord is called the spinal nerve root. Because of their position, spinal nerve roots can be squeezed (compressed) when the spine is injured, resulting in pain.
The lower (lumbar) spine connects the chest to the pelvis and legs, providing mobility—for turning, twisting, and bending. It also provides strength—for standing, walking, and lifting. Thus, the lower back is involved in almost all activities of daily living. Low back pain can limit many activities and reduce the quality of life.