Spinal cord

A cylinder of nerve tissue that runs from the brain, down the central canal in the spine to the 1st lumbar vertebra. Below that, the nerve roots continue within the canal as cauda equina. Grey matter, the spinal cord’s core, contains the cell bodies of nerve cells. Areas of white matter (tracts of nerve fibres running lengthwise) surround the grey matter. Sprouting from the cord on each side at regular intervals are the sensory and motor spinal nerve roots. The small nodule (ganglion) in each sensory root comprises nerve cell bodies. Nerve roots combine to form the spinal nerves that link the spinal cord to all regions of the trunk and limbs. The entire spinal cord is bathed in cerebrospinal fluid and surrounded by the meninges. The nerve tracts in the white matter act mainly as highways for sensory information passing up to the brain or motor signals passing down. However, the cord processes some sensory information itself and provides motor responses without involving the brain. Many reflex actions are controlled in this way. The spinal cord may be injured by trauma (see spinal injury); spinal-cord infections such as poliomyelitis are rare but can cause serious damage.