Introduction

Back pain is one of the most common reasons people visit their doctor. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, 8 out of 10 people have some type of backache.

Back pain can be acute, subacute, or chronic.

• Acute back pain develops suddenly and lasts up to several weeks. Acute pain is the most common type of back pain.
• Subacute back pain is pain that lasts up to 3 months.
• Chronic back pain can come on fast or slow, but it lasts longer than 3 months.

Back pain can occur in any area of the back, but it is more common in the lower back, which supports most of the body's weight.

The Spine

The back is highly complex, and pain may result from damage or injury to any of its various bones, nerves, muscles, ligaments, and other structures. Still, despite sophisticated techniques, which provide detailed anatomical images of the spine and other tissues, the cause of most cases of back pain remains elusive.

Vertebrae. The spine is a column of small bones, or vertebrae, that support the entire upper body. The column is grouped into three sections:

• The cervical (C) vertebrae are the seven spinal bones that support the neck.
• The thoracic (T) vertebrae are the twelve spinal bones that connect to the rib cage.
• The lumbar (L) vertebrae are the five lowest and largest bones of the spinal column. Most of the body's weight and stress falls on the lumbar vertebrae.

Below the lumbar region is the sacrum, a shield-shaped bony structure that connects with the pelvis at the sacroiliac joints.

At the end of the sacrum are two to four tiny, partially fused vertebrae known as the coccyx, or "tail bone."

Each vertebra is designated by using a letter and number, alllowing the doctor to determine where it is in the spine.

• The letter reflects the spinal region where thevertebra is located:
  • C=cervical (neck region)
  • T= thoracic (chest, or middle back, region)
  • L=lumbar (lower back)
• The number signifies the vertebra's place within that spinal region. The numbers start with 1 at the top of a region and count up as the vertebrae descend within the region. For example, C4 is the fourth bone down in the cervical region, and T8 is the eighth thoracic vertebrae.

The Disks. Vertebrae in the spinal column are separated from each other by small cushions of cartilage known as intervertebral disks. The disks have no blood supply of their own. They rely on nearby blood vessels to keep them nourished.

• Inside each disk is a jelly-like substance called the nucleus pulposus.
• The nucleus pulposus is surrounded by a tough, fibrous ring called the annulus.