Photographs by Hank and Jean Krebs with special thanks to our models DiAnn S and Amanda M for all their hard work and patience.

    The anatomical illustrations used throughout this manual are faithful reproductions of a lithograph plates from Gray's Anatomy, a two-dimensional work of art, is not copyrightable in the U.S. as per Bridgeman Art Library v. Corel Corp.; the same is also true in many other countries, including Germany. Unless stated otherwise, it is from the 20th U.S. edition of Gray's Anatomy of the Human Body, originally published in 1918 and therefore lapsed into the public domain.