IMAGING OF MUSCLE INJURIES

Although skeletal muscle is the single largest tissue in the body, the re is little written about it in the radiologic literature. Indirect m uscle injuries, also called strains or tears, are common in athletics, and knowing the morphology and physiology of the muscle-tendon unit i s the key to the understanding of these injuries. Eccentric muscle act ivation produces more tension within the muscle than when it is activa ted concentrically, making it more susceptible to tearing. Injuries in volving the muscle belly tend to occur near the myotendinous junction. In adolescents, the weakest link in the muscle-tendon-bone complex is the apophysis. Traditionally, plain radiography has been the main dia gnostic modality for evaluation of these injuries; however, with the a dvent of MRI it has become much easier to diagnose injuries primarily affecting the soft tissues. This article reviews the anatomy and physi ology of the muscle-tendon unit as they relate to indirect muscle inju ries. Examples of common muscle injuries are illustrated.