Abdominal viscera

Question 1

Name the 2 omentas and what do they derive from?

Answer 1

1) Greater omentum - from the dorsal mesentery

2) Lesser omentum - from the ventral mesentery

Question 2

To what does the greater omentum attach?

Answer 2

The greater omentum attaches to the greater curvature of the stomach and the first part of the duodenum

Question 3

Describe the route of the greater omentum

Answer 3

Inferior —- superior
Inferiorly ascends to cover the abdomen including the transverse colon and coils of the jejunum and ileum
Superiorly it becomes adherent to the peritoneum of the transverse colon superiorly and the anterior layer of the transverse mesocolon as it passes posteriorly and arrives at the posterior abdominal wall
It attaches to the greater curvatures of the stomach and the first part of the duodenum

Question 4

To what does the lesser omentum attach?

Answer 4

The lesser omentum attaches to the lesser curvature of the stomach and the first part of the duodenum as it rises to the inferior border of the liver

Question 5

Which 2 vessels are enclosed within the greater omentum peritoneal bi-layer just inferior to the greater curvature of the stomach?

Answer 5

The right and left gastro-omental vessels

Question 6

What 2 regions can the lesser omentum be divided into?

Answer 6

1) The hepatogastric ligament - medially, extending from the lesser curvature of the stomach to the inferior border of the liver
2) The hepatoduodenal ligament - laterally, extending from the first part of the duodenum to the inferior border of the liver

Question 7

What is the significance of the lateral margin of the hepatoduodenal ligament and what does it enclose?

Answer 7

The lateral margin of the hepatoduodenal ligament (the lateral region of the lesser omentum which extends from the first part of the duodenum to the inferior surface of the liver) is a free margin which serves as the anterior border of the epiploic (omental) foramen . The omental foramen is the gap between the lesser and greater omental sacs. Enclosed within the omental foramen is the hepatic artery proper, the portal vein and bile duct

Question 8

What causes paralytic ileus and how does the omentum react?

Answer 8

When a region of the colon is inflamed and thus stops peristaltic movements - this is paralytic ileus. The rest of the colon contiunes peristalsis while this region is aperistaltic - this causes massaging of the overlying greater omentum towards the aperistaltic region, to which the greater omentum then becomes adherent. This omental covering tries to reduce spread of the inflammation within the abdominal cavity

Question 9

1) What is the significance of the omentum with regards metastatic spread and in which cancer in particular
2) What is the name of the sign visible on CT due to metastatic spread throught the omentum?

Answer 9

1) Direct omental spread via a trans-coelomic route . Common in ovarian carcinoma
2) The omentum becomes significantly thickened - “omental cake”

Question 10

Which 2 vessels are contained between the layers of the lesser omentum and whereabouts are they?

Answer 10

The right and left gastric vessels near the lesser curvature of the stomach

Question 11

What is the generic structural role of the mesenteries - i.e. aside from providing a conduit for vessels and lymphatics?

Answer 11

To attach the viscera to the posterior abdominal wall

Question 12

What are the 3 mesenteries?

Answer 12

1) The Mesentery - associated with parts of the small intestine
2) The Transverse Mesocolon
3) The Sigmoid Mesocolon

Question 13

The mesenteries are derivatives of the…

Answer 13

The mesenteries are derivatives of the dorsal mesentery

Question 14

The mesentery connects what structures to the posterior abdominal wall?

Answer 14

The mesentery connects the jejunum and ileum to the posterior abdominal wall

Question 15

Describe the route of the mesentery

Answer 15

Superior attachment at the duodenojejunal junction just to the left of the upper lumbar part of the vertebral column
It passes obliquely downwards and to the right, ending at the ileo-caecal junction near the upper border of the right sacro-iliac joint

Question 16

What passes within the mesenteries and what do they supply / drain?

Answer 16

The vessels, nerves and lymphatics that supply the jejunum / ileum

Question 17

What structure does the transverse mesocolon connect to the posterior abdominal wall?

Answer 17

The transverse mesocolon connects the transverse colon to the posterior abdominal wall

Question 18

What passes within the transverse mesocolon and what do they supply / drain?

Answer 18

The vessels, nerves and lympathics supplying the transverse colon

Question 19

The …layer of the transverse mesocolon is adherent with the …. layer of the ……

Answer 19

The anterior layer of the transverse mesocolon is adherent with the posterior layer of the greater omentum

Question 20

What structure does the sigmoid mesocolon connect to the posterior abdominal wall?

Answer 20

The sigmoid mesocolon connects the sigmoid colon to the posterior abdominal wall

Question 21

Describe the shape of the sigmoid mesocolon and its route

Answer 21

The sigmoid mesocolon is an ‘inverted-V’ shape with its apex at the branching of the common iliac artery into the internal and external iliac arteries. The left limb of the ‘v’ passes near the medial border of the left psoas muscle and the right limb of the ‘v’ descends into the pelvis to end at the level of vertebra S3

Question 22

What passes within the sigmoid mesocolon and what do they supply / drain?

Answer 22

The sigmoid and superior rectal vessels along with the nerves and lymphatics associated with the sigmoid colon

Question 23

Name two peritoneal ligaments

Answer 23

1) Splenorenal ligament

2) Gastrophrenic ligament

Question 24

Describe the site of emergence of the abdominal oesophagus and the vertebral level

Answer 24

The abdominal oesophagus emerges from the right crus of the diaphragm at the oesophageal hiatus at vertebral level TX and then connects to the stomach at the pyloric orifice just left of the midline

Question 25

Describe the innervation of the abdominal oesophagus and where these fibres arise from

Answer 25

The anterior and posterior vagal trunks are associated with the abdominal oesophagus. The anterior vagal trunk is mainly composed of fibres from the left vagus and the posterior vagal trunk is mainly composed of fibres from the right vagus

Question 26

Describe which regions of the trunk the stomach is within (based on the 9 abdominal regions)

Answer 26

The stomach lies within the epigastric, umbilical and the left hypochondrium regions

Question 27

Describe the arterial supply to the abdominal oesophagus

Answer 27

The oesophageal branches of the left gastric artery (from the coeliac trunk)
The oesophageal branches of the left inferior phrenic artery (from the abdominal aorta)

Question 28

Which arteries supply the the stomach and what do they arise from?

Answer 28

The left gastric artery from the coeliac trunk
The right gastric artery from the hepatic artery proper

The right gastro-omental artery from the gastroduodenal artery
The left gastro-omental artery from the splenic artery
The posterior gastric artery from the splenic artery ( a variant which is not necessarily always present)