Vertebrate Bodies

A spine, or vertebral column, provides a solid support for the body but is flexible so the body can bend. This is possible because the column is built from smaller articulating blocks, or vertebrae, made of cartilage or bone. The power for bending comes from muscle blocks called myotomes that flank the column. The spines of the first vertebrates - fish - swung sinuously from side to side; this movement made them a success in water and later helped their for legged descendents crawl on land.