Overview of abdominal cavity

Question 1

Learning outcomes

Answer 1

• Identify the following bony landmarks: xiphoid process, costal margin, iliac crest, anterior superior iliac spine, pubic symphysis, pubic tubercle and pubic crest
• Identify and describe the location of the 9 regionsand 4 quadrantsof the abdomen
• Describe the peritoneal cavity and the terms ‘visceral peritoneum’ and ‘parietal peritoneum’
• Describe and identify the arrangement of the visceral and parietal peritoneum
• Describe the term ‘retroperitoneal’ and describe which organs and structures are defined as being retroperitoneal
• Describe the lymphatic drainage of the abdominal cavity

Question 2

Regions of the abdomen

Answer 2

Left and right hypochondrium, epigastric region, left and right flank, gastric region, left and right groin, pubic region
Transpyloric plane- Located mid-way between the jugular notch and the pubic symphysis or mid-way between the xiphoid process and the umbilicus

4 quadrants- right upper and lower, left upper and lower quadrants

Question 3

Peritoneum

Answer 3

• The peritoneum is a serous membrane that produces a small amount of peritoneal fluid

• There are two types of peritoneum:
• Parietal peritoneum – lines the abdominopelvic cavity
• Visceral peritoneum – covers abdominal and pelvic organs
• The peritoneal cavity is a potential spacebetween the parietal and visceral peritoneum and contains a small quantity of peritoneal fluid
• Peritoneal fluid is extremely important from a functional perspective: the fluid lubricates the surfaces of organs and contains white blood cells and antibodies

Question 4

Greater and lesser sacs

Answer 4

The peritoneal cavity is separated into 2 sacs
-Greater sac: accounting for the majority of the space within the peritoneal cavity
-Lesser sac (omental bursa): located posterior to the stomach
• The omenta and mesenteries are folds of peritoneum that are located within the abdominal cavity

• The omenta are double-layered folds of peritoneum and are known as the lesser and greater omenta

Question 5

Greater and lesser omenta

Answer 5

The lesser omentum is attached to the lesser curvature of the stomach and to the liver.

The greater omentum is attached to the greater curvature of the stomach.

Note that the greater omentum folds back on itself and attaches to the transverse colon.

Question 6

Mesentries

Answer 6

• Mesenteries are also double-layered folds of peritoneum e.g.

• Mesentery of the small intestine (The mesentery of the small intestine is firmly attached to the posterior abdominal wall and runs forwards to attach to the small intestine.)
• Transverse mesocolon (extends between the transverse colon and posterior abdominal wall and covers the anterior surface of the pancreas.)
• Sigmoid mesocolon

Question 7

Retroperitoneal organs and structures

Answer 7

Structures within the abdominal cavity that are not suspended by a mesentery and that are located between the peritoneum and the posterior abdominal wall are described as being retroperitoneal (e.g ascending colon)

Question 8

Embryological development and the foregut, midgut and hindgut

Answer 8

-During embryological development, the foregut gives rise to the oesophagus, stomach, liver, gall bladder, pancreas and the proximal duodenum
• The midgut gives rise to the distal duodenum, jejunum, ileum, caecum, appendix, ascending colon and the proximal two thirds of the transverse colon
• The hindgutgives rise to the distal one third of the transverse colon, descending colon, sigmoid colon, rectum and upper region of the anal canal

Question 9

Embryological development and arterial supply

Answer 9

Structures and organs arising from the foregut receive arterial supply from the coeliac trunk and it branches
The superior mesenteric artery and its branches supply structures and organs of the midgut
The inferior mesenteric artery and its branches supply structures and organs of the hindgut

Question 10

Lymphatic drainage of the abdominal cavity

Answer 10

• Lymph draining the structures and organs of the foregutdrains into pre-aortic lymph nodes located close to the origin of the coeliac trunk
• Lymph draining the structures and organs of the midgut drains into pre-aortic lymph nodes located close to the origin of the superior mesenteric artery
• Lymph draining the structures and organs of the hindgut drains into pre-aortic lymph nodes located close to the origin of the inferior mesenteric artery
• Lymph from all of these groups of pre-aortic lymph nodes drains into the cisterna chyli