Sacral vertebra and spinal cord. Light micrograph (LM) of a section through a vertebra and spinal cord. The vertebral body (top) and the spinous process (bottom) are formed of bone. The spinal cord lies centrally surrounded by thin meninges. Muscle surrounds the vertebra. Roots streaming caudally to join the cauda equina are evident surrounding the cord. Magnification: X 20 when printed at 10 centimetres wide.