Editing Sigmoid colon (section)

==Structure==
The sigmoid colon begins at the [[superior aperture]] of the [[lesser pelvis]], where it is continuous with the [[iliac colon]], and passes transversely across the front of the [[sacrum]] to the right side of the pelvis.

It then curves on itself and turns toward the left to reach the middle line at the level of the third piece of the [[sacrum]], where it bends downward and ends in the [[rectum]].

Its function is to expel solid and gaseous waste from the gastrointestinal tract. The curving path it takes toward the anus allows it to store gas in the superior arched portion, enabling the colon to expel gas without excreting faeces simultaneously.

===Coverings===
The sigmoid colon is completely surrounded by [[peritoneum]] (and thus is not [[retroperitoneal]]), which forms a [[mesentery]] ([[sigmoid mesocolon]]), which diminishes in length from the center toward the ends of the loop, where it disappears, so that the loop is fixed at its junctions with the [[iliac colon]] and rectum, but enjoys a considerable range of movement in its central portion.

===Nerve supply===
[[Pelvic splanchnic nerves]] are the primary source for [[Parasympathetic nervous system|parasympathetic]] innervation.  [[Lumbar splanchnic nerves]] provide [[Sympathetic nervous system|sympathetic]] innervation via the [[inferior mesenteric ganglion]].

===Relations===
Behind the sigmoid colon are the [[External iliac vessels (disambiguation)|external iliac vessels]], ovary, obturator nerve, the left [[piriformis]], and left [[sacral plexus]] of nerves.

In front, it is separated from the [[Urinary bladder|bladder]] in the [[male]], and the [[uterus]] in the [[female]], by some coils of the [[small intestine]].