Abstract
Pediatric physical therapists routinely evaluate and treat children who have medical conditions which directly or indirectly influence the growth and development of their musculoskeletal system. The musculoskeletal system demonstrates a remarkable ability to adapt to the physical demands, or lack of physical demands, placed on the system. Pathologic conditions and atypical motor or postural patterns may adversely influence the structure and function of any component of the system and may lead to impairments. The normal process of adaptation can either enhance function or lead to impairment, activity restriction, participation limitation, and decreased quality of life. The development and function of the musculoskeletal system and the neurologic system are intertwined. A neurologic condition such as cerebral palsy is often associated with muscle weakness and the development of muscle contractures. Therapeutic interventions are often designed to promote musculoskeletal adaptations to prevent or correct physical impairments, with the hope of enhancing function and participation. Accordingly, knowledge of normal growth and development and the principles of adaptation of the musculoskeletal system are essential for understanding the efficacy of interventions and preventing secondary impairments of this system. This chapter describes the typical growth and development of muscle and bone and provides a foundation for future chapters to describe the adaptations of muscle and bone during abnormal loading or developmental conditions that alter musculoskeletal development.