The urachus is a tube between the bladder and the belly button that is present before birth. In most cases, it closes along its full length before the baby is born. Another definition – the urachus is formed as the allantoic stalk during fetal development and lasts through life. Also called median umbilical ligament.
Is urachus a proper ligament? NO – the urachus is a tube-like structure present during fetal development that connects the developing bladder to the umbilical area. In a healthy fetus, the urachus typically closes off around the 12th week of gestation, forming a fibrous cord called the median umbilical ligament.
The lumen of the urachus usually obliterates following birth and becomes known as the median umbilical ligament which is in turn covered by a midline linear fibrous fold of parietal peritoneum (the median umbilical fold) 3. This fold extends from the apex of the bladder to the umbilicus. If you wish to know more