Vertebra. Coloured scanning electron micrograph (SEM) of a single vertebra,part of the vertebral column. It is composed of an anterior segment (top),called the vertebral body,which faces the chest,and a posterior segment (bottom),called the vertebral arch,which faces the back and encloses the vertebral foramen (hole in centre). When the vertebrae fit together,a semi-rigid,bony pillar is formed that supports the head,trunk and surrounding muscles. The vertebral foramina create a protected space,down which the spinal cord runs |