Since 1991 we have known that the entire abdominal musculature has a distinct resting tone. All other muscles lose their tension almost completely during the resting phase. Only the craniopharyngeal and anorectal sphincter systems retain natural spontaneous activity, which ceases only when a hollow organ is opened. This permanent natural spontaneous activity is extremely sensitive. For example, it increases during coughing and speech. With combined positron emission and computed tomography, it is possible to observe and measure this natural spontaneous activity in the adjacent musculature very clearly. This fact is important for understanding and therapy of the function and failure of sphincter systems.