a) Spinal cord is a part of the central nervous system. b) It is a downward continuation of the medulla oblongata. c) It is a long cylindrical structure protected by the vertebral column. d) It is composed of large number of nerve cells and nerve fibres. e) It has grey matter in the centre surrounded by white matter. f) 31 pairs of nerves arise from the spinal cord and their branches reach several parts like heart, lungs, stomach etc,. g) The spinal nerves are made up of both sensory and motor nerve fibres.