8. Development of the Digestive System and Peritoneal Membranes Flashcards

1
Q

What is the omental bursa?

A

The space between the stomach and the posterior body wall.

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2
Q

What is the origin, blood supply, nerve supply, and lymphatic drainage for the inferior one third of the anal canal?

A

Origin: ectoderm (proctodeum).

Blood supply: middle and inferior rectals.

Nerve supply: pudendal nerve.

Lymphatic drainage: superficial inguinal lymph nodes.

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3
Q

The spleen is a part of the foregut — so it’s endoderm derived, right?

A

NO, YOU IDIOT.

It’s mesoderm.

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4
Q

What gives rise to the falciform ligament of the liver?

A

The ventral mesentery.

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5
Q

How might esophageal atresia be diagnosed?

A

Insertion of an NG tube. If it coils after so many centimeters, esophageal atresia is confirmed.

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6
Q

When do the tracheoesophageal folds form, or if forming incorrectly, create a esophageal atresia / tracheoesophageal fistulae?

A

Week five

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7
Q

Why does the midgut have to leave the abdominal cavity and enter the umbilical cord?

A

Because it is growing faster than the abdominal cavity, because the liver is very large at this point (because it is performing hematopoiesis), and because the kidneys are taking up the length of the abdominal cavity as they are growing.

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8
Q

What would be the primary clinical difference between a symptomatic patient with an annular pancreas, and a symptomatic patient with pyloric stenosis?

A

In the case of the patient with pyloric stenosis, the vomit will be non-bilious because it hasn’t reached the major duodenal papilla.

In the case of the annular pancreas, the vomit can be bilious because it may have.

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9
Q

What are the 3 parts of the dorsal mesogastrium?

What does each part go-between?

A

The splenorenal ligament goes between the spleen and the posterior body wall, passing by the kidney.

The gastrosplenic ligament goes between the stomach and the spleen.

The greater omentum, which does its own thing.

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10
Q

In the G.I. system, what comes from mesoderm – and what layer of mesoderm are we talking about?

A

The mesoderm of the G.I. is splanchnic mesoderm, which gives rise to smooth muscle and connective tissue.

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11
Q

Where does the striated muscle of the esophagus come from?

A

Mesoderm of the fourth and sixth pharyngeal arches.

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12
Q

What all hindgut membranes are made of endoderm and ectoderm?

A

The urogenital membrane.

The anal membrane.

The cloacal membrane

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13
Q

During which week does the midgut enter the umbilical cord, and during which week does it return from the umbilical cord?

A

The midgut leaves at week 6, and returns at week 10.

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14
Q

What disintegrates leaving the transverse pericardial sinus?

A

The dorsal mesocardium.

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15
Q

What are the main characteristics of a congenital diaphragmatic hernia?

What is the cause?

A

Characteristics: Displacement of the heart – typically to the right side. Displacement of intestinal contents into the thorax. Lung hypoplasia. Polyhydramnios.

Failure of the pleuroperitoneal membranes to close, resulting in a foramen of Bochdalek.

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16
Q

What is the adult structure of the septum transversum called?

A

The central tendon of the diaphragm.

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17
Q

What causes Meckel’s diverticulum?

A

The vitelline duct pulling on the ileum creating a diverticulum.

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18
Q

What important G.I. structures come from the neural crest cells?

A

The autonomic ganglia of the plexus of Meissner and the plexus of Auerbach.

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19
Q

What are the intraperitoneal structures?

A

Liver

Stomach.

First 1/4 of the duodenum.

Tail of pancreas.

Jejunum and Ileum.

Transverse colon.

Sigmoid colon.

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20
Q

What are the urogenital membrane and the anal membrane made out of embryo logically?

A

Ectoderm and endoderm

21
Q

What is the foramen of Bochdalek?

A

A large hole (typically on the left side) which forms as a result of the failure of the pleuroperitoneal membranes to close.

22
Q

What structures arise from the midgut?

A

Distal duodenum (after the major duodenal papilla).

The rest of the small intestine.

The cecum.

The vermiform (cecum) appendix.

The ascending colon.

The proximal (right) half of the transverse colon.

23
Q

What is the function of the dorsal mesogastrium?

A

Gives rise to the greater omentum.

24
Q

What embryological layer does that the pleuroperitoneal membrane come from?

A

Somatic layer of the lateral plate mesoderm.

25
Q

What structure grows ventrally out from the foregut just below the stomach?

A

The hepatic diverticulum.

26
Q

What structures come from the foregut?

A

The pharynx (and derivatives).

The esophagus.

The respiratory system (!).

The stomach.

The liver and pancreas.

The biliary apparatus.

The proximal duodenum (up to the major duodenal papilla).

27
Q

What is the total rotation of the midgut?

A

90° in the umbilical cord, 180° when it returns.

A total of 270° rotation.

28
Q

What structures form from the urogenital membrane?

A

The bladder and urethra.

29
Q

When does bile start being produced?

A

The 12th week

30
Q

What structures arise from the hindgut?

A

Distal (left) half of the transverse colon.

Descending colon.

Sigmoid colon.

Rectum.

The superior anal canal.

The epithelium of the urinary bladder and urethra.

31
Q

What is the rule of twos for Meckel’s diverticulum?

(6 things)

A

Affects 2% of the population.

Occurs 2 feet from the ileocecal junction.

The diverticulum is 2 inches long.

Contains 2 types of ectopic tissue (gastric and pancreatic).

Presents at 2 years of age.

Affects males 2 times as often.

32
Q

What is the axis of rotation for the midgut?

A

The superior mesenteric duct.

33
Q

What is the mesentery “proper.”

A

The mesentery containing the ileum and jejunum.

34
Q

What is a gastroschisis?

During what week might it occur?

A

The failure of the body wall to close.

Week 4 (this is when the anterior body wall closes).

35
Q

What are the secondary retroperitoneal structures?

A

Pancreas (except tail).

Duodenum (parts 2-4).

Ascending and Descending colon.

36
Q

Which structures arise from the ventral primordia of the pancreas?

A

Most of the head of the pancreas, as well as the main pancreatic duct.

37
Q

When does development of the stomach occur?

A

In the fourth week

38
Q

What embryological tissue forms the mucosa of the esophagus?

A

Foregut endoderm

39
Q

What is an omphalocele?

During what week does it occur?

A

A failure of the midgut to return to the abdominal cavity.

Week 10

40
Q

During which weeks does the liver perform hematopoiesis?

A

Weeks 6 to weeks 30

41
Q

What is the function of the ventral mesogastrium?

A

Gives rise to the lesser omentum.

42
Q

What is a mesentery?

A

A mesentery is a double layer of serous membrane, or a double layer of splanchnic mesoderm.

43
Q

What gives rise to the right and left crus of the diaphragm?

A

The dorsal mesentery of the esophagus.

44
Q

What is an annular pancreas?

A

Improper rotation of a bifid ventral pancreatic primordia fusing with the dorsal pancreatic primordia but forming a ring around the duodenum.

45
Q

What embryological layer is the urorectal septum made out of?

A

Mesoderm

46
Q

What structures arise from the hepatic diverticulum?

A

The ventral pancreatic bud, the gallbladder, the hepatic and bile ducts, and the liver bud.

47
Q

From what embryological origin do the hematopoietic cells of the liver arise?

A

From mesoderm (unlike the rest of the parenchyma which comes from endoderm).

48
Q

What is the origin, blood supply, nerve supply, and lymphatic drainage for the superior two thirds of the anal canal?

A

Origin: hindgut.

Blood supply: inferior mesenteric artery.

Nerve supply: “autonomics.”

Lymphatic drainage: inferior mesenteric lymph nodes.

49
Q

What embryological layer does the septum transversum come from?

A

The somatic layer of the lateral plate mesoderm.