The human spine is a column of 33 ring-like bones (vertebrae) that are separated from each other by 23 puck-shaped discs. These discs are made of cartilage and are filled with a gel-like center or nucleus.

• Each disc functions as a shock absorber against up-down stress (such as running, jumping, gravity). Discs also function as a kind of “ball bearing” that helps the upper body to move (bending over, twisting from side to side).
• The “hollow” of each ring-like vertebra forms the spinal canal, which houses and protects the spinal cord. The spinal cord is the “trunk” of the nervous system.
• Thirty-one pairs of spinal nerves branch off between the vertebrae and travel out to both sides of the body, branching and rebranching over and over, to supply various organs and tissues with nerve endings that command movement and sense heat and pressure.
• In and around the spine are tendons, ligaments, and muscle, all of which contribute to stabilization and strength.

There are 5 spinal regions, which conveniently allow groups of individual vertebra to be named. Starting at the top with the neck, these 5 regions are the cervical vertebrae (C1–7), thoracic vertebrae (T1–12), lumbar vertebrae (L1–5), the sacrum (S), and the coccyx.

• 7 cervical (neck) vertebrae — The topmost part of the cervical vertebrae is called the atlas, which, like its mythical namesake, bears the weight of the world (your head) on its shoulders. Under the atlas, with no disc between, is the axis, the pivot point for the head, followed by 5 more cervical vertebrae.
• 12 thoracic (chest) vertebrae — These 12 vertebrae provide attachment points for 12 pairs of ribs.
• 5 lumbar (lower back) vertebrae — The lumbar vertebrae are the largest vertebrae in the spine, and the discs around them bear the weight of the entire upper body. This section of the lower back is subject to hundreds of pounds of force and the constant stress of gravity.

• The lumbar vertebrae and the 6 discs around them are main region involved in discogenic lower back pain.

• Sacrum — The sacrum is actually 5 fused vertebrae. It provides a point of attachment for the pelvis.
• Coccyx —The coccyx is 4 fused vertebrae. It is thought to be an evolutionary remnant—a vestigial tail.

There are 23 intervertebral discs, from C2 down to the sacrum. There are no discs between fused vertebrae, between the coccyx and sacrum, and between the atlas and axis.

• Each disc is a puck-like capsule made up of a tough outer section called the anulus fibrosus and an elastic middle section called the nucleus pulposus.
• The fiber-like outer layers of the disc and its associated nerve endings are the target of the IDET procedure.

• In childhood, discs might be compared to fluid-filled or gel-filled sacs. As we age, however, the anulus toughens, the nucleus becomes much more solid than gel-like, and the disc becomes less elastic. By middle age, our discs may have the consistency of hard rubber, and their capacity to absorb shock is significantly decreased.
• As we age, our discs may also tend to flatten or “lose height.” One of the more reliable factors for predicting successful outcome with the IDET procedure is disc height.
• Patients who have lost 50% or more of their original disc height are not considered good candidates for IDET.

If you have chronic lower back pain, consult a physician. He or she may be able to compare your signs and symptoms with a list of criteria for diagnosing discogenic lower back pain. For further information see Symptoms and Diagnosis of Discogenic Lower Back Pain.

The lumbar region of the spine—the discs and vertebrae between T12 and the sacrum—is the lower back.

The fibrous outer layers of the disc make up what is known as the anulus. The anulus is where the nerve endings that cause discogenic lower back pain are found. The IDET procedure delivers heat to the tissues and nerve endings in the anulus. The anulus surrounds a gel-like center or nucleus. Unlike the annulus, the nucleus contains no nerve endings.