We describe here the temporomandibular joint and masticatory muscle abnormalities disclosed by computed tomography and magnetic resonance imaging in a 25-year-old man with centronuclear myopathy (a congenital myopathy) who presented with marked limitation of jaw movements. We found an intense and general fatty replacement of the masticatory muscles, and magnetic resonance imaging signals indicated articular fibrosis. We conclude that in centronuclear myopathy, the presence of weakness and hypomotility of the masticatory muscles can induce chronic abnormalities of the temporomandibular joint.