With every edition, our goal is powerful but simple -- to make anatomy and physiology as engaging, accurate, and relevant as possible for both instructors and students. The Ninth Edition represents a monumental revision, with changes to the text and art presentation that build upon the hallmark strengths of the previous eight editions. The changes to the Ninth Edition are all driven by the needs of today's students, as we seek to make the learning of key concepts in A&P as easy as possible for them. Key concepts are important because of the overwhelming amount of material in this course. Mastering this material gives students structure for organizing this wealth of information.