GI embryology Flashcards

1
Q

What 2 planes does embryonic folding in 4th week occur? Why? Folding in horizontal plane forms what? Medial plane?

A

Horizontal and medial planes
Differing rates of growth
2 lateral body folds
Cranial and caudal folds

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2
Q

Primitive gut tube from what layer? During what week does oropharyngeal membrane rupture to form the mouth? What week does cloacal membrane future–> anal canal?

A

Endoderm
4th week
7th week

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3
Q

What are pharyngeal arches part of? Extends from what to what? When do these develop?

A

Foregut
Oropharyngeal membrane–> resp diverticulum
4th and 5th week

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4
Q

What are pharyngeal arches formed from? Covered externally and internally from what?

A

Masses of mesenchymal tissue invaded by cranial neural crest cells
Externally= from endoderm–> clefts, internally= ectoderm–> pouches

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5
Q

1st arch innervated by what? What muscles? What bones?

A

Mandibular nerve- V3
Mastication, tensor tympani, digastric, myolohyoid
Maxilla, mandible, incus, malleus

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6
Q

2nd arch innervation? Muscles? Bones?

A

Facial nerve
Facial expression, stapedius, stylohyoid
Stapes, styloid, lesser horn of hyoid cartilage

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7
Q

3rd arch innervation? Muscles? Bones?

A

Glossopharyngeal nerve
Stylopharyngeus of pharynx
Body and greater horn of hyoid cartilage

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8
Q

4th arch innervation? Muscles? Bones?

A

Superior laryngeal nerve of vagus nerve
Cricothyroid
Thyroid and epiglottic cartilages

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9
Q

6th arch innervation? Muscles? Bones?

A

Recurrent laryngeal nerve of vagus nerve
All muscles except cricothyroid
Cricoid cartilage, arytenoid cartilages, corniculate and cuneiform cartilages

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10
Q

What septum separates the resp diverticulum from dorsal part of foregut? Foregut divided into what? Oesophagus is what initially but does what?

A

Trancheoesophageal septum
Ventral resp primordium and dorsal oesophagus
Short but lengthens rapidly with descent of heart and lungs

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11
Q

Where is ventral mesentery only present? Midgut and hindgut only what?

A

Only in foregut- terminal oesophagus, stomach and upper duodenum
Only dorsal mesentery

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12
Q

Ventral mesentery is derived from what? Free lower margin contains what? Liver develops where?

A

Septum transversum
Hepatic artery, portal vein and bile duct
In ventral mesentery- divides it into lesser omentum and falciform ligament

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13
Q

Stomach appears in foregut in what week? Does dorsal or ventral wall grow faster?

A

4th week

Dorsal grows faster- forms greater and lesser curvatures

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14
Q

During what week does stomach undergo 90 degrees clockwise rotation? During what week does stomach and duodenum rotate about a ventrodorsal axis?

A

7th week- produces lesser sac

8th week- pulls stomach upwards and duodenum into C-shape

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15
Q

Rotations results in what? Ventral mesentery forms what? Anterior and posterior folds of greater omentum fuse to form what?

A

Thinning of dorsal mesentery–> greater omentum
Lesser omentum
One thick sheet formed from 4 layers of peritoneum

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16
Q

During what week does hepatic diverticulum appear? When does bile duct form? What gives rise to the gallbladder and cystic duct?

A

3rd week- as outgrowth of endodermal epithelium at distal end of foregut
When connection between liver diverticulum and foregut narrows
Small ventral outgrowth from bile duct

17
Q

Further growth of liver bud allows epithelial liver cords to intermingle with what? Liver cords differentiate into what?

A

The umbilical and vitelline veins–> hepatic sinusoids

Hepatocytes- form lining of biliary ducts

18
Q

During what week does mesoderm of ventral mesentery give rise to haematopoietic cells, Kipper cells and connective tissue cells?

A

6th week

19
Q

At 10th week, liver what % of total body weight? % at birth? Cells start bile production at what age? Haematopoietic function subsides when?

A

10%
5%
12th week
During last 2 months of intrauterine life

20
Q

Where does pancreas develop from? Where is each bud?

A

Endodermal lining of duodenum as dorsal and ventral buds
Ventral bud from ventral mesentery
Dorsal bud from dorsal mesentery

21
Q

When the duodenum rates and becomes C-shaped, what happens? What fuses together?

A

The ventral bud and entrance to common bile duct in duodenum are shifted dorsally- lies below and behind dorsal bud
Parenchyma and duct systems of both buds fuse together

22
Q

The ventral bud forms what? Dorsal bud forms what?

A

Uncinate process and inferior of head

Rest of pancreas

23
Q

Main pancreatic duct formed from what? Islets of Langerhans from what during what month of fetal life? Insulin secretion begins when? Pancreatic connective tissue from what?

A

Union of ventral pancreatic duct with distal part of duct of dorsal bud
Parenchyma of pancreas at 3rd month
At 5th month
Visceral surrounding mesoderm