There are 31 pairs of spinal nerves that branch out from the spine at regularly spaced intervals corresponding to the vertebrae. Each nerve consists of two functional branches, or roots, and serves as a conduit for both incoming sensory information and outgoing motor commands. The spine is also categorized in five segments

• cervical (neck)
• thoracic (trunk)
• lumbar (lower back)
• sacral (pelvic)
• coccygeal (bottom)