Chapter 016. Back and Neck Pain (Part 1) Harrison's Internal Medicine > Chapter 16. Back and Neck Pain Back and Neck Pain: Introduction The importance of back and neck pain in our society is underscored by the following: (1) the cost of back pain in the United States is ~$100 billion annually, including direct health care expenses plus costs due to loss of productivity; (2) back symptoms are the most common cause of disability in those <45 years; (3) low back pain is the second most common reason for visiting a physician in the United States; and (4) ~1% of the U.S. population is chronically disabled because of back pain. Anatomy of the Spine The anterior portion of the spine consists of cylindrical vertebral bodies separated by intervertebral disks and held together by the anterior and posterior longitudinal ligaments. The intervertebral disks are composed of a central gelatinous nucleus pulposus surrounded by a tough cartilaginous ring, the annulus fibrosis; disks are responsible for 25% of spinal column length (Figs. 16-1 and 16-2). The disks are largest in the cervical and lumbar regions where movements of the spine are greatest. The disks are elastic in youth and allow the bony vertebrae to move easily upon each other. Elasticity is lost with age. The function of the anterior spine is to absorb the shock of body movements such as walking and running. Figure 16-1 Vertebral anatomy. (From A Gauthier Cornuelle, DH Gronefeld: Radiographic Anatomy Positioning. New York, McGraw-Hill, 1998; with permission.) Figure 16-2 Spinal column. (From: A Gauthier Cornuelle, DH Gronefeld: Radiographic Anatomy Positioning. New York, McGraw-Hill, 1998; with permission.) . Chapter 016. Back and Neck Pain (Part 1) Harrison's Internal Medicine > Chapter 16. Back and Neck Pain Back and Neck Pain: Introduction The importance of back and neck pain. years; (3) low back pain is the second most common reason for visiting a physician in the United States; and (4) ~1% of the U.S. population is chronically disabled because of back pain. Anatomy. the following: (1) the cost of back pain in the United States is ~$100 billion annually, including direct health care expenses plus costs due to loss of productivity; (2) back symptoms are