The editor of the old standby medical text "Gray's Anatomy" says the drawings of the body are nothing more than road maps for doctors.

Susan Standring lectured in Philadelphia's Mutter Museum Wednesday on the parallel development of geographic maps used by explorers and what she calls "maps of the body."

In medieval times, both land and body maps were heavily influenced by faith. A Christian map of the world might place Jerusalem at the center, Standring said. A drawing of the body then may have had a circle in the head, to represent the soul.

"Early maps were very much conceptual, they were maps based on religious belief," Standring said. "You couldn't have found your way around the world, and neither could you have found your way around the body using those kinds of maps."

During the Renaissance, when explorers needed to navigate, maps became more based on the physical world.

"And of course, in anatomical maps, people started to dissect, they wanted to look at the body the way it really was," Standring said.

Standring said parallels in development have continued. For example, schematic maps are used to represent the London Underground and the system of neuronal connectivity.

They don't show what a system looks like, exactly, but how all the pieces all work together.