The vertebral column, also called the spine, provides support for the trunk of the body, protects the spinal cord, and provides attachment points for the ribs and muscles of the back and trunk.

The spine has 4 natural curves. This "S" shape allows for it to act more like a spring for the body rather than a straight stiff rod and helps to provide resilience for bearing the weight and motion of the body.

The vertebral column consists of 5 major divisions:

  1. 7 cervical vertebrae
  2. 12 thoracic vertebrae
  3. 5 lumbar vertebrae
  4. Sacrum
  5. Coccyx

Located between the individual vertebrae are cushions called intervertebral disks. These disks act like shock absorbers during physical activity such as walking, jumping, or lifting, and allow the spine to extend and flex.

Each vertebra and disk is named by its division and order. For example, the first lumbar vertebra is called "L1", the second is called "L2" and the disk in between is called the "L1 - L2 intervertebral disk." The lumbar portion of the spine supports most of the body's weight and is the most common area for back pain.

The vertebrae are designed to help protect the spinal cord and the spinal nerves that extend from the spinal cord to the various parts of the body. The protection of the spinal cord and its nerves are important for maintaining good body function and health. Each intervertebral disk consists of 2 parts. The center of the disk is called the nucleus pulposus, which acts like a rubber ball to provide cushioning during compression. The nucleus pulposus is surrounded by a tough fibrous outer covering called the annulus fibrosus. The annulus fibrosus protects the nucleus pulposus and keeps its jelly-like material contained within the disk.

Over time or as a result of injury, the outer covering of the disk may wear out or become torn. If this happens, the center jelly-like material may bulge out and put pressure on a nearby spinal nerve. The protrusion or rupturing of a disk is often called a "slipped disk." This condition may result in severe pain or even limit motion and your ability to do certain physical activities.

Other common causes of low back pain are:

  • Narrowing of the spinal canal, also called spinal stenosis
  • Small fractures to the vertebral bodies
  • Strains or tears of the muscles, tendons, or ligaments that support the spine
  • Poor alignment of the vertebrae
  • Spasms of the muscles in the back

Various treatments are available for low back pain, including medication, physical therapy, chiropractic treatments, acupuncture, massage therapy, and surgery. However, the best medicine of all is prevention through proper exercise, keeping good posture during working and resting times, and maintaining healthy living habits.


Main Menu

Review Date: 4/6/2007

Benjamin D. Roye, M.D., M.P.H., Orthopaedic Surgery, The Mount Sinai Hospital, New York, NY. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Related Links
Find an Orthopaedic Surgeon
Request an Appointment Online or call
1-800-789-PENN (7366)
Penn Orthopaedics
Encyclopedia Articles about Bones and Joints




About Penn Medicine   Contact Us   Site Map   Privacy Statement   Legal Disclaimer   Terms of Use

Penn Medicine, Philadelphia, PA 800-789-PENN © 2016, The Trustees of the University of Pennsylvania space