To be an effective practitioner of any physical therapy an understanding of kinesiology (how muscles work), biomechanics (principles of joint action), and the interaction of muscle groups is essential. This knowledge is only possible through a strong grounding in the structure of the muscles and their relationship to the skeletal system. This module introduces the major muscles, muscle groups, their attachments and structural components. It also reviews the skeletal system with special emphasis on the joints and the structural elements of cartilage and tendons that are so vital to the function of movement and are so commonly involved where there is pain and injury.