The sigmoid colon works to move stool from inside the colon to the rectum. It accomplishes this through muscular contractions.
The colon, which is also referred to as the large intestine, is divided into four parts, including the ascending, transverse, descending and sigmoid sections. The sigmoid colon, which is shaped like the letter "S," lies just outside the rectum. Other than expelling solid waste from the gastrointestinal tract, the sigmoid colon also expels gaseous waste. Its curved design allows for gas storage and expulsion without excreting solid waste at the same time. The sigmoid colon is separated by the uterus in the women and the bladder in men.