The Anatomy of Back Pain

• Irritation to the large nerve roots that exit the spine and go down the legs and arms
• Irritation to the smaller nerves in the spine
• Strain on the large muscles in the back
• Injury to the bones, ligaments or joints in the spine

1. Cervical Spine (neck) - has seven vertebral bodies (segments), and most of the rotation in the neck occurs in the top two segments.
   
   
2. Thoracic Spine (upper back) - has twelve vertebral bodies (segments) and has its motion limited by the support of the rib cage, making this region of the spine less susceptible to injuries. However, the ribs do connect with the spine by way of a synovial joint and these joints often become irritated by postural stress, tension or fast rotational movements of the spine (such as when starting a lawn mower). This can lead to a nagging, painful condition that often goes misdiagnosed.
   
   
3. Lumbar Spine (lower back) - has five vertebral bodies (segments) that run from the lower thoracic spine to the sacrum. The sacrum is at the bottom of the spine and lies between the bottom lumbar segment and the coccyx (tailbone).

• Discs
  
  The disc is an interesting and unique structure. Its primary purpose is to act as a shock absorber. Discs are actually composed of two parts: a tough outer material and a soft (gel filled) inner core.
  
  The disc is originally composed of mostly water. Over time, however, the discs dehydrate and become stiffer and for some individuals this can be a source of pain. The theory is that the degeneration can produce a tiny amount of instability and the soft inner core of the disc probably leaks out of the disc space and inflames the nerve roots next to the disc.
  
  Sometimes a twisting injury damages the disc and can eventually lead to degeneration. In general, as we age there are less inflammatory proteins in the disc space and it is rarely a cause of pain after 6o years of age.
  
  
• Soft Tissues
  
  The soft tissues around the spine can also be painful. An injury to the large back muscles (or tension and stress) can cause the muscles to become inflammed and spasmed, resulting in pain and limited motion.
  
  If the pain lasts for more than two weeks, the muscles can start to weaken, and muscle weakness can in turn lead to more pain because the muscles are less able to help hold up the spine.
  
  Another structure that plays a role in back pain is the hamstring muscles in the leg. Patients with tight hamstrings tend to develop low back pain, and those with low back pain tend to develop tight hamstrings. The theory is that tight hamstrings limit motion in the pelvis, so the motion gets transferred to the bottom lumbar motion segments and increases the stress in the spine.
  
  Finally, ligaments and tendons that attach from one structure to another in the spine can become injured and cause pain.