Each vertebra represents a level of the spine, and therefore of the spinal cord. At each level, some of the spinal cord branches away from the center to become individual nerves. The individual nerves branch out further and further. The nerves collectively form a network all over the human body.
The place where the cord first branches away from the main body is called the nerve root. There is a nerve root on either side of each of the vertebrae.
The route that each nerve takes as it leaves the spinal cord and branches out into the body is called a dermatome. Each nerve has a dermatome, and each dermatome contains many nerves.
The significance of a dermatome is that the nerves that travel through the particular dermatome routes affect the area in which their dermatome is located. Nerves affect the dermatome in 2 ways:
- sensory - felt sensation
- motor - ability to move