Anatomy

The spinal cord and nerves carry impulses to and from your brain. The spine is a collection of bones, ligaments, discs, and other tissue that support and protect the spinal cord and the spinal nerves. Unfortunately, if any of this protective tissue presses on a nerve or stretches it, your brain interprets that pressure as pain, tingling, or some other unpleasant sensation, and this sensation feels to you like it’s coming from a distant part of your body (for example, your foot).
The spine is a set of alternating bones and discs. Each bone is called a vertebra. The discs act like shock absorbers for the vertebrae. They also make it possible for you to bend your spine. Each disc has two layers. The inner layer is the nucleus and the outer layer is the annulus. Think of these two layers like a car tire. The outer layer (the annulus or the tire’s rubber) is strong, and the inner layer (the nucleus or the tire's air) supplies the cushion.