Anatomy of the spinal cord and brain

Abstract

The central nervous system (CNS) is divided into a rostral brain and a caudal spinal cord. The brain is contained in the cranial cavity, and the spinal cord is located in the vertebral canal that is formed by the 31 vertebral foraminae from the individual vertebra. The two are continuous with one another at the foramen magnum of the occipital bone. Any neural structure that lies outside the pia mater covering of the CNS is considered part of the peripheral nervous system. Therefore, the 12 pairs of cranial nerves, which arisefrom the brain, and the 31 pairs of spinal nerves originating from the spinal cord with their associated ganglia are, by convention, part of the peripheral nervous system. Both the brain and spinal cord are organized into gray matter, where the neuronal cell bodies are located and white matter, which contains the long myelinated tracts of the CNS. Spinal cord gray matter is centrally located and surrounded by white matter, whereas the opposite occurs in the cerebral cortex.