Back pain is one of the most common complaints that individuals have to their doctors. Nearly 65 million Americans report having recently suffered back discomfort. Some 16 million individuals, or 8% of all adults, suffer from persistent or chronic back pain, limiting their ability to engage in various daily activities. Back problems are the number one reason for missed work days. The vertebral column consists of the bones of the spine (including the skull) and their supporting structures. It is made up of seven cervical (neck) segments, twelve dorsal (back) segments, five lumbar (low back) segments, and four sacral (base of the spine) segments. Each segment has a characteristic curve called a lordosis or kyphosis. The curves of the different segments help to support the body's weight as well as provide flexibility for day-to-day movement. There are many factors that can lead to back problems including being overweight or obese, lack of physical activity, smoking, alcohol abuse, eating disorders such as anorexia nervosa or bulimia nervosa, stress, depression, and use of drugs and/or medications that can cause back pain. Older individuals are more likely to experience back problems due to natural changes in the bone structure that can lead to increased risk of injury or instability. Women are more likely than men to experience back problems during pregnancy because of hormonal changes that can increase the risk of injury to the spine.