has part has part has_part characteristic of part of has modifier abnormal smooth muscle morphology abnormal anal canal morphology abnormal internal anal sphincter morphology MP:0009055 abnormal internal sphincter muscle of anus abnormal musculus sphincter ani internus MPheno.ontology any structural anomaly of the smooth muscle ring, formed by an increase of the circular muscle fibers of the rectum, situated at the upper end of the anal canal, internal to the outer voluntary external anal sphincter morphology abnormal internal anal sphincter