Anatomy Of The GI system 1

Question 1

Summarize the organize the peritoneal cavity

Answer 1

Developing gut invaginate into the peritoneal cavity. Organization of peritoneal cavity :
▪ Greater and Lesser sac
▪ Supracolic and infracolic spaces
▪ Ligaments - e.g. Greater and lesser omentum
▪ Spaces – For clinical purposes the peritoneal cavity can
be divided into several spaces because pathological processes are often contained in these spaces and their anatomy may influence diagnosis and treatment

Question 2

What is a peritoneum?

Answer 2

Peritoneum is a continuous serous membrane which surrounds the organs of abdominal cavity and lines the abdominopelvic wall.

Provides mobility for some & stability for others via reflection points & fusion points

Question 3

What are the two layers of the peritoneal cavity?

Answer 3

Parietal peritoneum – lines the internal surface of abdominal wall

Visceral peritoneum – clothes the abdominal organs

Question 4

What is the parietal peritoneum derived from?

Answer 4

Parietal peritoneum –somatopleure Innervated by somatic afferents from the spinal nerves associated with the region of the abdominal wall where it is located
Pain from the parietal peritoneum is usually well localized

Question 5

What is the visceral peritoneum derived from?

Answer 5

Visceral peritoneum-splanchnopleure Innervated by visceral afferents which accompany autonomic nerves supplying the organ in question
Pain is usually poorly localized and usually presents as sensations of discomfort

Question 6

What is the peritoneal cavity?

Answer 6

Potential space between the parietal and visceral layers .

Secretes small amount of fluid which lubricates the surface of the peritoneum and allows free movement of viscera

Excess fluid in the peritoneal cavity is called ascites

Question 7

What is the pneumoperitoneum?

Answer 7

Pneumoperitoneum -Abnormal presence of air/gas in the peritoneal cavity
generally due to a ruptured hollow viscus organ

Question 8

What is peritonitis?

Answer 8

Peritonitis is inflammation of the peritoneum

Question 9

What is the peritoneal cavity?

Answer 9

Abdominopelvic cavity –space bounded by the abdominal walls, diaphragm and pelvis
The peritoneum and viscera are in the abdomino-pelvic cavity

Question 10

Where is the peritoneal cavity?

Answer 10

Peritoneal cavity lies between the two layers of peritoneum and is one continous space
– Extends from the diaphragm to the pelvis
– Male system closed/ Female open at uterine tube
– There are no organs in the peritoneal cavity

Question 11

What are ascites?

Answer 11

ASCITES = abnormal fluid within peritoneal cavity ie between visceral and parietal layers

Question 12

What is the mesentery?

Answer 12

Double fold of peritoneum that attaches the developing gut to the body wall. Contains blood vessels nerves and lymphatics

All embryonic gut tube structures including the spleen develop on a mesentery

Question 13

What is the relationship of viscera to peritoneum?

Answer 13

Intraperitoneal organs Completely covered by visceral peritonuem

Extraperitoneal ,retroperitoneal organs: Organs that are outside the
Peritoneal cavity or posterior to the parietal peritoneum. Usually covered by peritoneum on one surface.

Eg: kidney is between the parietal peritoneum and the posterior abdominal wall and have peritoneum only on their anterior surface.

Question 14

What does it mean to be an intraperitoneal organ?

Answer 14

Intraperitoneal
Pushes into peritoneal sac Covered by visceral peritoneum

Suspended by mesentery
(2 layers of peritoneum)

Question 15

What are Retroperitoneal organs ?

Answer 15

Retroperitoneal: behind peritoneal sac

Primarily Retroperitoneal
Never pushed into peritoneal sac

Secondarily Retroperitoneal
Was pushed into the sac developmentally but is not in adult

Question 16

What are the intraperitoneal organs?

Answer 16

Intraperitoneal organs
(have a mesentery)
• Stomach
• Liver
• Duodenum 1st part
• Small intestine (jejunum, ileum)
• Spleen
• Cecum and Appendix
• Transverse & Sigmoid colon

Question 17

What are the primarily retroperitoneal organs?

Answer 17

Primarily Retroperitoneal
(posterior body wall behind peritoneum)
• Kidneys
• Ureters
• Aorta
IVC
• Sympathetic trunks

Question 18

What are the secondary retroperitoneal organs?

Answer 18

Pancreas
Duodenum 2nd,3rd & 4th part 
Ascending colon 
Descending colon
Rectum

Question 19

Where do gut structures start their development?

Answer 19

• All gut structures start their development on a mesentery
• Throughout the course of development i.e. rotation of the gut, the mesentery fuses with the posterior abdominal wall. Peritoneum only covers the anterior surface. Therefore the structure that once intraperitoneal now is secondarily retroperitoneal.
• Secondary retroperitoneal structures are fixed (immobile)

Question 20

What is the significance of ventral and dorsal mesentery?

Answer 20

Ventral and dorsal mesentery
•Foregut –stomach, liver, proximal duodenum and spleen is connected to anterior and posterior abdominal walls by ventral and dorsal mesentery/ mesogastrium.

• As a result of clockwise stomach rotation ventral mesentery and liver is pushed to the right forming the lesser omentum, falciform, coronary and triangular ligaments.

•Stomach rotation also causes dorsal mesentery to be pulled to the left forming the
greater omentum (gastrocolic ,gastrosplenic ,splenorenal and gastrophrenic ligaments.

•Dorsal mesentery continues as mesentery of the small intestines and mesocolon of the large intestines

Question 21

What are peritoneal ligaments?

Answer 21

Peritoneal ligaments:-double layer of peritoneum that connects an organ with another organ or to the anterior abdominal wall. They support the organ in position and may convey their neurovascular structures.

Question 22

What is the omentum?

Answer 22

Omentum: double layer of peritoneum

Passing from the stomach and proximal part of the duodenum to adjacent organs

Question 23

What is the greater omentum?

Answer 23

Greater omentum: double layer of peritoneum extending from stomach to transverse colon

Question 24

What is the lesser omentum?

Answer 24

Lesser omentum: double layer of peritoneum attaching liver to the stomach and first part of duodenum

Question 25

What is the significance of the lesser omentum?

Answer 25

Extends from the inferior surface of the liver to the lesser curvature of the stomach and proximal duodenum and contains two ligaments :

•Hepatogastric ligament –membranous portion
Contains : gastric arteries
•Hepatoduodenal ligament - thickened portion
Contains:
1. Portal vein
2. Proper hepatic artery
3. Common bile duct

Question 26

What is the significance of the greater omentum?

Answer 26

• Gastrophrenic ligament –to diaphragm
• Gastrosplenic ligament- to spleen
• Gastrocolic ligament – to the transverse colon and mesocolon

Greater omentum has ascending and descending portions of the greater omentum usually fuse together forming a four layered (2anterior+2 posterior) fatty
“omental apron”

Normally reffered to as the policeman of the abdomen

Question 27

What is the clinical correlation of greater omentum?

Answer 27

Compression of the hepatoduodenal ligament (Pringle maneuver) prevents inflow of blood into the liver thereby reducing bleeding in the liver as a result of
traumatic injury

Question 28

What are the greater and lesser sac?

Answer 28

Greater sac main and larger part of the peritoneal cavity.

Lesser sac /Omental bursae is the smaller part of the peritoneal cavity, lies posterior to the stomach lesser omentum and adjacent structure

Question 29

What is the significance of peptic ulcer?

Answer 29

Perforation of a peptic ulcer of the stomach along its posterior wall will result in blood collecting in the lesser sac which could then communicate with the greater sac through the omental foramen

Question 30

Whaat is the omental foramen?

Answer 30

The communication between the lesser sac and greater

Question 31

What is The anterrior boundary of omental foramen?

Answer 31

Hepatoduodenal ligament with portal triad

Question 32

What is the inderior boundary of the omental foramen?

Answer 32

Duodenum (superior part)

Question 33

What is the posterior part of the omental foramen?

Answer 33

Inferior vena cava

Question 34

What is the superior order of the omental formen?

Answer 34

Caudate lobe of the liver

Question 35

What are the subdivisions of the peritoneal cavity?

Answer 35

The mesentery of the transverse colon divides the cavity into a supracolic compartment and an infracolic compartment

Question 36

What are supracolic compartment contains?

Answer 36

• Stomach
• Liver
• Spleen

Question 37

What does the infracolic compartment?

Answer 37

Infracolic compartment conatins:.
Small intestine

•Ascending colon and descending colon The infra-colic compartment lies posterior
to the greater omentum and is further divided into right and left infra colic spaces by the small intestine.

Communication between the supracolic and infracolic compartments are through the paracolic gutters

Question 38

What are the clinical correlations of the paracolic gutters?

Answer 38

Depressions between the lateral margins of the ascending and descending colon and the posterolateral abdominal wall.

Because major vessels and lymphatics are on the medial or posteromedial sides of the ascending and descending colon, a relatively blood-free mobilization of the ascending and descending colon is possible by cutting the peritoneum along these lateral paracolic gutters.

The left paracolic gutter is narrower and partially obstructed by the phrenicolic ligament. Therefore it is easier for infection to travel to the right subphrenic space

Question 39

What are the boundaries of the pouch of Morisson (hepatorenak recess)?

Answer 39

Boundaries
Anterior : Liver
Posterior : right kidney
Inferior :transverse colon

Question 40

Whaat is the clinical correlate of the pouch of morisson?

Answer 40

The hepatorenal recess is the most dependent space for the collection of pathological fluid in the supine patient

Question 41

What is the clinical relevance of the hepatoduodenal ligament?

Answer 41

Question 42

Where is the lesser sac located?

Answer 42

Question 43

What are the boundaries of lesser sac/ o mental bursae?

Answer 43

Question 44

WHat are the boundaries of the pouch of Morrison ?

Answer 44