Myositis Ossificans: A disease characterized by bony deposits or the ossification of muscle tissue.Myositis: Inflammation of a muscle or muscle tissue.Temporal Muscle: A masticatory muscle whose action is closing the jaws; its posterior portion retracts the mandible.Ankylosis: Fixation and immobility of a joint.Technetium Tc 99m Medronate: A gamma-emitting radionuclide imaging agent used primarily in skeletal scintigraphy. Because of its absorption by a variety of tumors, it is useful for the detection of neoplasms.Ossification, Heterotopic: The development of bony substance in normally soft structures.Myositis, Inclusion Body: Progressive myopathies characterized by the presence of inclusion bodies on muscle biopsy. Sporadic and hereditary forms have been described. The sporadic form is an acquired, adult-onset inflammatory vacuolar myopathy affecting proximal and distal muscles. Familial forms usually begin in childhood and lack inflammatory changes. Both forms feature intracytoplasmic and intranuclear inclusions in muscle tissue. (Adams et al., Principles of Neurology, 6th ed, pp1409-10)Activin Receptors, Type I: One of the two types of ACTIVIN RECEPTORS or activin receptor-like kinases (ALK'S). There are several type I activin receptors. The major active ones are ALK-2 (ActR-IA) and ALK-4 (ActR-IB).Hallux: The innermost digit of the foot in PRIMATES.