The prototype of this text was developed 8 years ago in response to a perceived need for a single source that would provide entry-level knowledge in biomechanics, muscle physiology, joint structure, and coordinated muscular function for physical therapy students. Through the years the content was modified and broadened in response to feedback from students and practitioners, as well as reviews of recent literature. What evolved was a transdisciplinary text that not only encompasses basic theory required to understand normal and pathologic function, but also provides the foundation for understanding current trends in musculoskeletal evaluation and treatment.