part_of part of part of skeletal muscle of trunk Note that this class excludes smooth muscle elements in the trunk region, such as the internal anal sphincter. This appears to be consistent with other ontologies such as FMA and ZFA which appear to only include skeletal muscles here. In fact the MA class 'trunk muscle' is classified as a 'set of skeletal muscles'. Many ontologies do not appear to have a coherent distinction between an individual muscle and the musculature (i.e. the set of muscles in a region), so we group all together here. trunk musculature of trunk trunk region element skeletal muscle organ