The peritoneum - ANATOMY

Question 1

What is the peritoneum?

Answer 1

Inner lining of the abdominal caviity, containing a single continuous cell layer - squamous

Mesothelium

Question 2

What is the difference between the peritoneal and abdominal cavity?

Answer 2

Peritoneal is contained in the peritoneum and

Question 3

What is contained in the peritoneal cavity? What is it analogous to?

Answer 3

Peritoneal fluid

• Potential space
  
  • Cavity

Organs are contained . in peritoneal reflections
- Mesenteries

Analogous to pleural cavity, where the lungs are suspended.

Question 4

What does the GI tract consist of? What are the three regions?

Answer 4

Mouth and pharynx
Esophagus
Stomach

Duodenum
Jejunum, Ilium
Caecum, large intestine

Sigmoid colon, rectum and anus

Thoracic, ? and pelvic respectively

Middle region can be palpated

Question 5

Embryologically, when does the gut tube develop?

Answer 5

4th week of life

Question 6

How does the gut develop?

Answer 6

Mesoderm and endoderm invaginate, leading to the formation of the gut tube

It is suspended from the posterior abdominal wall by a peritoneal fold
- dorsal mesentery

Question 7

What are mesenteries?

Answer 7

Folds in the peritoneum that attach viscera to the abdominal wall

Conduit for the vessels , nerves and lymphatics.

Question 8

Define splanchnic

Answer 8

Something that pertains to an organ and does not ‘stick’ to a wall - check

Question 9

What are the types of peritoneum?

Answer 9

Visceral
- Peritoneum that covers suspended organs

Parietal
- Lining the abdominal wall

Question 10

What are the types of structure with respect to relationship with peritoneum?

Answer 10

INTRAparietal

• suspended from abdominal wall by mesenteries - in peritoneal cavity
• Small intestine

RETROparietal

• lies between parietal peritoneum and abdominal wall
• posterior abdominal wall

Question 11

Give some examples of retroperitoneal organs

Answer 11

Kidneys, vessels, oesophagus, rectum, nerves

Duodenum
Pancreas
Colon
- intraparietal but then became retro as the mesenteries fused w body wall

Question 12

How is the GI tract divided?

Answer 12

Foregut
- Distal 1/3 of oesophagus to the 2nd part of duodenum - bile duct

Midgut
- 2nd part of the duodenum to 2/3 along transverse colon

Hindgut
- Distal third of transverse colon to rectum

They all have different blood supplies and different nervous systems

Question 13

How is the gut tube supported?

Answer 13

Dorsal mesentery

BUT, foregut has a ventral mesentery - contains pancreas, liver etc

Question 14

What are the two sacs?

How is the lesser formed?

Answer 14

Lesser

• Omental bursa
• Contains liver and stomach only
• Formed when liver moves to the right, and mesentery and spleen move left forming a cavity to the posterior side
• Situated in space posterior to between stomach and liver

Greater

Question 15

What is the greater omentum? How does it communicate with the lesser sac?

Answer 15

Apron that extends anterior to intestine, communicates with lesser sac via epiploic foramen

Question 16

Which structures run through the lesser omentum?

Answer 16

HPV, hepatic artery and bile duct

Between liver and posterior abdominal wall

The free section is present due to the ending of the ventral mesentery

Question 17

What are the peritoneal compartments?

Answer 17

Supracolic compartment

Transverse colon mesentery - marks junction for supra or infra colic compartments

Infracolic compartment

Left and right paracolic gutter - for asc and desc large intestine

Small intestine mesentery

Question 18

How does fluid move in the peritoneum? What is the importance?

Answer 18

Upwards, towards underside of diaphragm

If cancer of the colon, and some cells are discarded, can move up and cause metastasis

Question 19

How about inflammatory exudate?

Answer 19

Towards pelvis

Question 20

What is the ‘general plan’ of the GI tract?

Answer 20

In to out
All muscles in GI are SMOOTH

Mucosa 
- has muscularis mucosae
   - for mucus movement
Submucosa
Muscularis
- inner circular
- outer longitudinal
Serosa
Mesentery

Question 21

How does the oesophagus enter the abdomen?

Answer 21

Pierces diaphragm at T10

• muscular part
  
  • this contributes to LOWER OESOPHAGEAL SPHINCTER
  • prevents food from going back up

Question 22

Summarise the structure of the stomach

Answer 22

Top to bottom

Fundus
Body
Pyloric antrum
Pyloric canal

(Clinical note – on chest x-rays be aware that you can often see a gas bubble in the fundus of the stomach lying directly beneath diaphragm. Do not confuse this air bubble with air in the peritoneum, say from an intestinal perforation.)

Question 23

Outline the structure of the small intestine

Answer 23

Duodenum
Jejunum
Ileum

Question 24

Outline the structure of the duodenum

Answer 24

Duodenal cap - superior
Major duodenal papilla - descending - pancreatic . duct
Inferior
Ascending

MOSTLY RETROPERITONEAL

Question 25

Outline the structure of the jejunum and ileum

Answer 25

Proximal and distal parts respectively J is larger J has LESS prominent arterial arcades J has longer vasa recta

Question 26

What does the large intestine consist of? What distinguishes it from the small intestine?

Answer 26

``` Caecum Ascending colon Transverse colon Descending colon Sigmoid colon ``` Fatty tags Ribbons of longitudinal muscles

Question 27

WHich arteries supply the gut?

Answer 27

Arise from the aorta Foregut - liver, pancrease and spleen - COELIAC TRUNK Midgut - SUPERIOR MESENTERIC ARTERY Hindgut - INFERIOR MESENTERIC ARTERY

Question 28

What are the branches of the coeliac trunk?

Answer 28

Left gastric Common hepatic Gastroduodenal Splenic

Question 29

What are the branches of the superior mesenteric artery?

Answer 29

Middle, right, ileo -colic arteries Jejunal and Ileal arteries

Question 30

What are the branches of the inferior mesenteric artery?

Answer 30

Left colic Superior rectal Sigmoid Anastomosis occurs here where we have switching from superior to inferior arteries

Question 31

Describe venous drainage of the abdomen and how they lead to portal vein

Answer 31

Splenic vein Portal vein Inferior mesenteric Superior mesenteric Inferior goes into splenic, goes into superior mesenteric, becomes portal

Question 32

What are porto-systemic anastomoses?

Answer 32

When blockage occurs and leads to venous dilation.

Question 33

How is the gut innervated?

Answer 33

Viscera - AUTONOMIC - Parasympathetic sensory regulates reflec gut function - Vagus nerve - Pelvic splanchnic nerve - Sympathetic PAIN - Thoracic and lumbar splanchnic