Terms

References

The nervous system is made up of the central nervous system, the peripheral nervous system, and the cranial nerves. The spinal cord, part of the central nervous system, is generally around 17 inches long, and extends from the brain to the lower back. It is protected by the vertebral column (also known as the spinal column or backbone), which consists of 33 vertebrae (26). Three membranes, meninges, cover both the brain and spinal cord (1, 31). The subarachnoid space is filled with cerebrospinal fluid (1) which provides shock absorbance (26). The vertebrae are divided into sections depending on their location. (26)

cervical vertebrae- the first 7 vertebrae, located in the neck

thoracic vertebrae- the next 12 vertebrae in the upper back

lumbar vertebrae- 5 vertebrae located in the lower back

5 fused sacral vertebrae located around the hip

4 fused vertebrae in the coccyx

The peripheral nerves branch off of the cervical, thoracic, lumbar and sacral regions, and are named according to their origin on the spinal column. Letters and numbers, which correspond to the level of the spine, are often used when referring to the location of the injury. For example, a C4 injury is located at the forth level in the cervical segment (26). The nerves leading out of each section of the spinal cord connect to specific regions of the body. The cervical nerves (C1-C8) control signals to the arms, neck and hands. The thoracic nerves (T1-T12) control the signals to the torso and parts of the arms. The lumbar nerves (L1-L5) relay signals to the legs and hips, and the sacral nerves (S1-S5) control signals to the toes, groin, and parts of the legs (21)

All information traveling from the brain to the limbs must travel through the spinal cord, and conversely all sensory information coming from the body is relayed to the spinal cord and then to the brain (1). Due to this arrangement, the damage caused by a spinal cord injury is determined by the location of the injury (21)