# Peritoneum and Its Reflections > Peritoneal reflections — omenta, mesenteries, ligaments, paracolic gutters and peritoneal spaces explained for MBBS Anatomy exams. - Canonical URL: https://prepelephant.com/topics/mbbs/anatomy/peritoneum-reflections - Exam / course: MBBS · Subject: Anatomy - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Peritoneum and Its Reflections", PrepElephant, https://prepelephant.com/topics/mbbs/anatomy/peritoneum-reflections ## Direct answer The greater peritoneal sac is not one open pool but a set of compartments, gutters and folds created by the reflections that suspend the gut. Omenta hang from the stomach, mesenteries carry vessels to intestine, and ligaments connect organ to organ or organ to wall. The root of the mesentery of the small intestine is only about 15 cm long yet suspends 6 to 7 metres of jejunum and ileum, and the right and left paracolic gutters beside the ascending and descending colon are the highways along which infected fluid travels from a perforated appendix to the subphrenic spaces. ## What you must remember - **Greater omentum:** a four-layered apron hanging from the greater curvature, wrapping inflammation and sealing perforations — the "policeman of the abdomen". - **Lesser omentum:** hepatogastric and hepatoduodenal ligaments from the liver hilum to the stomach and duodenum; its free right edge carries the portal triad. - **Mesentery root:** about 15 cm, from the duodenojejunal flexure (left of L2) obliquely down to the ileocaecal junction; the whole small bowel mobile on this narrow base. - **Other mesenteries:** transverse mesocolon crossing the pancreas at about L2, and the sigmoid mesocolon whose inverted-V apex points at the left ureter and the bifurcation of the common iliac artery. - **Right paracolic gutter:** communicates freely upwards with the right subphrenic and subhepatic spaces (Morison's pouch) and downwards into the pelvis — the classical route of a subphrenic abscess after appendiceal perforation. - **Left paracolic gutter:** blocked above by the phrenicocolic ligament (sustentaculum lienis) at the lower pole of the spleen, so fluid on the left tends to settle in the pelvis instead. - **Ligaments worth naming:** gastrosplenic (short gastric and left gastroepiploic vessels), splenorenal (splenic vessels and tail of pancreas), falciform (ligamentum teres — the obliterated left umbilical vein), and coronary ligaments bounding the bare area of the liver. ## Tracing a drop of infected fluid A 30-year-old man has a perforated appendix. Pus escapes into the right paracolic gutter, and the story of the peritoneal reflections now decides his disease. Lying supine, his most dependent upper abdominal space is Morison's pouch, the hepatorenal recess between liver and right kidney; the paracolic gutter delivers the infected fluid straight there. From Morison's pouch it can rise to the right subphrenic space, which explains why a subphrenic abscess can appear weeks after a "settled" appendicitis, and why the right dome of the diaphragm, not the left, classically collects free gas on an erect film — the bare area binds the liver's posterior surface to the diaphragm and the right subphrenic space is the largest gas attic. On the left the plumbing differs. The phrenicocolic ligament, acting as a shelf supporting the spleen, cuts the left paracolic gutter off from the left subphrenic space, so left-sided collections pool in the pelvis or under the left lobe instead. Below, both gutters drain freely into the pelvic recesses — rectovesical or rectouterine — which is why pelvic abscesses follow generalized peritonitis and why a pelvic collection is sought by rectal or vaginal examination at the most dependent peritoneal point. ## Where students slip The umbilical folds are quoted carelessly, and examiners pounce. The ligamentum teres in the falciform ligament is the obliterated left umbilical vein; the median umbilical ligament is the urachus from the bladder apex; the medial umbilical ligaments are the obliterated umbilical arteries. Confusing vein with urachus turns a caput medusae answer into a congenital anomaly answer. A second trap: calling the lesser omentum the "gastrohepatic ligament" alone — the hepatoduodenal part with the portal triad is the surgically critical half. In viva, expect the peritoneal relations of the spleen, whose gastrosplenic and splenorenal ligaments carry the vessels a surgeon must control. ## Frequently asked questions ### Why does a perforated appendix cause a subphrenic abscess? Infected fluid ascends the right paracolic gutter from the ileocaecal region into the right subhepatic (Morison's pouch) and then the subphrenic space, because the gutter is unobstructed on the right. ### What is the length and attachment of the root of the mesentery? About 15 cm, from the duodenojejunal flexure at the level of L2 to the ileocaecal junction, running obliquely across the posterior abdominal wall. ### What is the phrenicocolic ligament and why does it matter? A peritoneal fold from the left colic flexure to the diaphragm that supports the spleen and cuts off the left paracolic gutter from the left subphrenic space, redirecting left-sided fluid to the pelvis. ### What are the contents of the splenorenal ligament? The splenic artery and vein and the tail of the pancreas — the reason a splenectomy and a pancreatic injury go together. ### What is Morison's pouch? The right subhepatic recess between the liver and right kidney, the most dependent intraperitoneal space in the supine position, where fluid collects first. ### Which peritoneal fold contains the obliterated umbilical vein? The falciform ligament, containing the ligamentum teres — the obliterated left umbilical vein, which can recanalise in portal hypertension.