Human Anatomy
Abdominal Cavity
Abdominal cavity for MBBS: peritoneum and sacs, gut blood supply, stomach, duodenum, liver, spleen and appendix, and portosystemic anastomoses, mapped to NMC codes AN47.1 to AN47.14.
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Abdominal Cavity
Abdominal cavity for MBBS: peritoneum and sacs, gut blood supply, stomach, duodenum, liver, spleen and appendix, and portosystemic anastomoses, mapped to NMC codes AN47.1 to AN47.14.
The abdominal cavity chapter covers the peritoneum and its sacs, the arterial supply of the gut by the three midline vessels, and the major organs including the stomach, duodenum, liver, spleen and appendix. It is the anatomical foundation for abdominal surgery, portal hypertension and appendicitis.
High-yield: Abdominal Cavity
- The peritoneum is a serous membrane with a parietal layer lining the wall and a visceral layer covering the organs.
- The peritoneal cavity is divided into a greater sac and a lesser sac, connected through the epiploic foramen.
- The epiploic foramen, or foramen of Winslow, is bounded in front by the free edge of the lesser omentum containing the portal triad.
- The stomach is supplied along its curvatures by branches of the coeliac trunk.
- The coeliac trunk supplies the foregut, the superior mesenteric artery the midgut and the inferior mesenteric artery the hindgut.
- The midgut extends from the second part of the duodenum to two-thirds along the transverse colon.
- The duodenum is mostly retroperitoneal and is closely related to the head of the pancreas.
- The portal vein is formed behind the neck of the pancreas by the union of the splenic and superior mesenteric veins.
- Portal hypertension opens portosystemic anastomoses at the lower oesophagus, the anal canal and the umbilicus.
- The spleen lies in the left hypochondrium along the axis of the ninth to eleventh ribs and is not normally palpable.
- The appendix arises from the caecum, and its base lies at McBurney's point in the right iliac fossa.
- The position of the appendix is most often retrocaecal, which affects the signs of appendicitis.
- The liver receives a dual blood supply from the hepatic artery and the portal vein.
- The gall bladder lies at the tip of the ninth costal cartilage, where its fundus can be felt in disease.
Gut arterial supply and midgut landmarks
- **Coeliac trunk:** Supplies the foregut: stomach, liver, spleen, upper duodenum and pancreas.
- **Superior mesenteric artery:** Supplies the midgut, from mid-duodenum to two-thirds of the transverse colon.
- **Inferior mesenteric artery:** Supplies the hindgut, from the distal transverse colon to the upper anal canal.
- **Portal system:** Portal vein formed behind the pancreas. Portosystemic sites: oesophagus, anus, umbilicus.
NMC competencies in this chapter
- **AN47.1:** Peritoneum: parietal and visceral layers and reflections
- **AN47.2:** Greater and lesser sacs and the epiploic foramen
- **AN47.3:** Stomach: relations, blood supply and lymphatic drainage
- **AN47.4:** Duodenum, pancreas and their relations
- **AN47.7:** Liver, biliary apparatus and gall bladder
- **AN47.8:** Spleen and its relations
- **AN47.11:** Caecum, appendix and colon
- **AN47.13:** Portal vein and portosystemic anastomoses
Frequently Asked Questions
How is the gut blood supply divided?
The coeliac trunk supplies the foregut, the superior mesenteric artery the midgut and the inferior mesenteric artery the hindgut, matching the developmental divisions of the gut.
Where are the portosystemic anastomoses?
At the lower oesophagus, the anal canal and around the umbilicus. These open up in portal hypertension, causing oesophageal varices, piles and caput medusae.
Where is McBurney's point?
It is at the junction of the outer and middle thirds of a line from the umbilicus to the right anterior superior iliac spine, marking the base of the appendix.
How does this chapter help in NEET-PG?
Gut blood supply, the portal system and organ relations are central to general surgery and radiology, so the abdominal cavity is heavily tested at PG level.
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