Spinal cord:Themajorcolumn ofnervetissue连接to thebrainand lies within the vertebral canal and from which the spinal nerves emerge. Thirty-one pairs of spinal nerves originateinthespinal cord: 8cervical, 12thoracic, 5lumbar, 5sacral, 1coccygeal. The spinalcordand the brain constitute thecentral nervous system. The spinal cord consists of nerve fibers that transmit impulses to and from the brain. Like the brain, the spinal cord is covered by three connective-tissue envelopes called themeninges. The space between the outer and middle envelopes is filled withcerebrospinal fluid(CSF), a clear colorless fluid that cushions the spinal cord against jarring shock. Also known simply as the cord.
