The spinal cord is the principle route for the passage of sensory information to and from the brain. The spinal cord is a long column of nerve tissue that extends from the base of the brain, (the medulla oblongata) downward through a canal created by the spinal vertebral foramina, usually terminating around the first lumbar vertebra.

The spinal cord is enveloped and protected by the vertebra of the spinal column. There are four regions of vertebrae. Beginning at the skull and moving downward, these are the eight cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five sacral vertebrae, and one coccygeal vertebra. The sacral and coccygeal vertebrae are also known as the tailbone. In cross-section, the vertebrae appear as a flat plate-like region (body) with antler-like projections (processes) perched above much like a hat. Between the body and the processes there is an open space called...