Low Back Pain
(Lumbar Back Pain)

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Low back pain facts

  • Functions of the low back, or lumbar area, include structural support, movement, and protection of certain body tissues.
  • Pain in the low back can be a result of conditions affecting the bony lumbar spine, discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, and the skin covering the lumbar area.
  • Treatment of low back pain is optimally directed toward a diagnosed or suspected specific cause. For acute lumbar strain, use of a home remedy initially can be beneficial.

What is the anatomy of the low back?

The first step to understanding low back pain is appreciating the normal design (anatomy) of the tissues of this area of the body. Important structures of the low back that can be related to symptoms in this region include the bony lumbar spine (vertebrae, singular = vertebra), discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, and the skin covering the lumbar area.

The bony lumbar spine is designed so that vertebrae "stacked" together can provide a movable support structure while also protecting the spinal cord from injury. The spinal cord is composed of nervous tissue that extends down the spinal column from the brain. Each vertebra has a spinous process, a bony prominence behind the spinal cord, which shields the cord's nervous tissue from impact trauma. Vertebrae also have a strong bony "body" (vertebral body) in front of the spinal cord to provide a platform suitable for weight bearing of all tissues above the buttocks. The lumbar vertebrae stack immediately atop the sacrum bone that is situated in between the buttocks. On each side, the sacrum meets the iliac bone of the pelvis to form the sacroiliac joints of the buttocks.

The discs are pads that serve as "cushions" between the individual vertebral bodies. They help to minimize the impact of stress forces on the spinal column. Each disc is designed like a jelly donut with a central, softer component (nucleus pulposus) and a surrounding, firm outer ring (annulus fibrosus). The central portion of the disc is capable of rupturing (herniating as in a herniated disc) through the outer ring, causing irritation of adjacent nervous tissue and sciatica as described below. Ligaments are strong fibrous soft tissues that firmly attach bones to bones. Ligaments attach each of the vertebrae to each other and surround each of the discs.

The nerves that provide sensation and stimulate the muscles of the low back as well as the lower extremities (the thighs, legs, feet, and toes) all exit the lumbar spinal column through bony portals, each of which is called a "foramen."

Many muscle groups that are responsible for flexing, extending, and rotating the waist, as well as moving the lower extremities, attach to the lumbar spine through tendon insertions.

The aorta and blood vessels that transport blood to and from the lower extremities pass in front of the lumbar spine in the abdomen and pelvis. Surrounding these blood vessels are lymph nodes (lymph glands) and tissues of the involuntary nervous system that are important in maintaining bladder and bowel control.

The uterus and ovaries are important pelvic structures in front of the pelvic area of women. The prostate gland is a significant pelvic structure in men. The kidneys are on either side of the back of the lower abdomen, in front of the lumbar spine.

The skin over the lumbar area is supplied by nerves that come from nerve roots that exit from the lumbar spine.

What is the function of the low back?

The low back, or lumbar area, serves a number of important functions for the human body. These functions include structural support, movement, and protection of certain body tissues.

When we stand, the lower back is functioning to support the weight of the upper body. When we bend, extend, or rotate at the waist, the lower back is involved in the movement. Therefore, injury to the structures important for weight bearing, such as the bony spine, muscles, tendons, and ligaments, often can be detected when the body is standing erect or used in various movements.

Protecting the soft tissues of the nervous system and spinal cord as well as nearby organs of the pelvis and abdomen is a critical function the lumbar spine and adjacent muscles of the low back.

Medically Reviewed by a Doctor on 6/10/2014

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Low Back Pain Treatment

Epidural Steroid Injection

Epidural steroid injections are most commonly used in situations of radicular pain, which is a radiating pain that is transmitted away from the spine by an irritated spinal nerve. Irritation of a spinal nerve in the low back (lumbar radiculopathy) causes pain that goes down the leg. Epidural injections are also used to treat nerve compression in the neck (cervical spine), referred to as cervical radiculopathy, which causes pain.