lower uterine segment http://purl.obolibrary.org/obo/NCIT_C12312 http://purl.org/sig/ont/fma/fma17752 https://en.wikipedia.org/wiki/Uterine_isthmus A09.1.03.012 An elongated constriction of the lower part of the uterus, located at the junction of the body of the uterus and the cervix, that is composed principally of smooth muscle. LUS isthmus of uterus uterine isthmus isthmus uteri zone of body of uterus