The central canal of the spinal cord contains cerebrospinal fluid. The pleural fluid surrounds the lungs, interstitial fluid surrounds the cells of multicellular animals, and aqueous humour is the fluid present between the lens and the cornea of the eye.
The spinal cord is made up of bundles of nerve fibres. It runs down from the brain through a canal in the centre of the bones of the spine. These bones protect the spinal cord. Like the brain, the spinal cord is covered by the meninges and cushioned by cerebrospinal fluid. Spinal nerves connect the brain with the nerves in most parts of the body. Other nerves go directly from the brain to the eyes, ears, and other parts of the head. This network of nerves carries messages back and forth between the brain and the rest of the body.
- The spinal cord is divided into four different regions: the cervical, thoracic, lumbar and sacral regions.
- The cord is sheathed in the same three meninges as is the brain: the pia, arachnoid and dura.