Morphologic Variations of the Umbilical Ring, Umbilical Ligaments and Ligamentum Teres Hepatis

PURPOSE The varied morphology of the umbilical ring and its surrounding structures, such as the ligamentum teres hepatis, and the median and medial umbilical ligaments, has not been thoroughly investigated. Hence, this study was undertaken to clarify the morphologic variations of these structures. MATERIALS AND METHODS The anterior abdominal walls were removed en bloc from 57 adult cadavers and dissected under a surgical microscope. RESULTS One case of umbilical hernia was observed, and the remaining 56 umbilical rings were classified into 3 types: oval or round in 33 cases (Type A, 59.0%), obliterated or slitted in 12 cases (Type B, 21.4%), and completely covered by a connecting band between the ligamentum teres hepatis and umbilical ligaments in 11 cases (Type C, 19.6%). The median and medial umbilical ligaments were classified into four types based on their interrelationships. The most common type was the median umbilical ligament terminated by joining one or both medial umbilical ligaments (Type II, 41.1%). The ligamentum teres hepatis frequently ended by dividing into several branches in the area cranial to the umbilical ring, some of which crossed the umbilical ring. The umbilical fascia covered the umbilical ring in 50.0% of cases, and the rest either not covering the ring or not existing. CONCLUSION These results are expected to improve our understanding of the anatomy of the umbilical area, and further improve treatments of the umbilical hernia.