Spinal Cord & Nerve Roots
Within the vertebral column is the spinal cord, a slender cylindrical structure with a diameter about as large as that of the little finger. The spinal cord begins immediately below the brain stem and extends to the first lumbar vertebra (the first vertebra of the lower back area). At that point, the spinal cord blends with the conus medullaris, which becomes the cauda equina, a group of nerves resembling the tail of a horse.
The spinal cord may be thought of as an “information highway” to the brain. The brain and spinal cord taken together make up the central nervous system (CNS). Information to and from nerves throughout the body travel via the spinal cord back and forth to the brain. Nerve roots exit the spinal canal (the area around the spinal cord) through small hollows and opening between the vertebrae. These nerve roots spread and branch out through the body and compose the peripheral nervous system (PNS). In this way, if you touch something hot with your hand, the nerves in the hand send out signals through the PNS to the CNS, where the brain interprets the signal and sends out a “return message” to move your hand away from the heat. Every day, hundreds of thousands of such message go back and forth through the spinal cord.
There are four principal sets of nerves associated with the spinal cord: cervical nerves (in the neck area), thoracic nerves (in the area of the ribs), lumbar nerves (in the lower back) and sacral nerves (in the “tailbone” area).
Connects the spinal cord to other parts of the brain.
Carries nerve impulses between the brain and spinal nerves.
Cervical Nerves (8 pairs):
Carry messages affecting the head, neck, shoulders, arms, and hands.
Thoracic Nerves (12 pairs):
Carry messages affecting the upper abdomen and muscles in the back and chest areas.
Lumbar Nerves (5 pairs):
Carry messages affecting the lower back and legs.
Sacral Nerves (5 pairs):
Carry messages affecting the buttocks, legs, feet, anal and genital areas of the body.
Describes the area on the surface of the skin that is supplied by nerve fibers from one spinal root