Lecture 17: Establishing the Body Cavities and Formation of the Diaphragm Flashcards Preview

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Flashcards in Lecture 17: Establishing the Body Cavities and Formation of the Diaphragm Deck (29):
1

Intraembryonic Coelem

Formed at beginning of fourth week. Vesicles in the lateral mesoderm coalesce, forming a horse-shoe shaped cavity

2

Functions of Intraembryonic Coelem

Continuous with extra-embryonic coelem (the space external to the yolk-sac), gives space for organs to grow into

3

Cranial-Caudal folding

The brain and tail regions grow quicker than the rest of the body, causing the embryo to fold into itself around the yolk sac

4

Lateral folding

The lateral edges of the germ disk fold towards each other, ventrally, caused by rapid growth of amnion and somites. Fuse in the midline. The yolk sac (made of endoderm) pinches off and becomes narrow and more tubular.

5

Regions of yolk sac after lateral folding

Foregut, midgut, hindgut

6

Mesoderm lining periteneal cavity

splanchnic mesoderm layer

7

Periteneal Cavity

What embryonic coelem is called after lateral folding is complete

8

Mesoderm lining the anterior body wall

somatic mesoderm layer

9

Dorsal Mesenteries

Suspends the gut tube (former yolk sac) within the periteneal cavity from dorsal side in caudal, foregut, midgut, hindgut

10

Ventral mesenteries

Suspends the gut tube from ventral side, only present in proximal foregut (stomach and doedunum)

11

Mesentery

A double layer of periteneum that connects organs to the body wall. Vessels and nerves travel through the mesentery, especially those supplying the gut

12

parts of embryonic body cavity

Pericardial cavity, peritoneal cavity, connected by 2 pericardial-peritoneal canals

13

Arterial supply to fore-gut

celiac artery

14

arterial supply to midgut

Superior mesenteric artery

15

Arterial supply to hindgut

Inferior mesenteric artery

16

Physiological herniation of midgut

The midgut sticks into the extraembryonic coelem from the intraembryonic coelem until week 10, at which point the intestine retreats into the intraembryonic coelem. After lateral folding the communication between the two coelems becomes much narrower, and only exists in one cross-section.

17

Parts of the diaphragm

The Septum transversum
Pleuroperitoneal membrane
dorsal mesentery of the esophagus
muscular growth of lateral body wall

18

Septum Transversum

Thick plate of mesodermal tissue, occupies the space between the pericardial cavity and the omphaloenteric duct. Originally were cranial to the developing heart, after cranio-caudal folding migrates to sit to above location.

19

Omphaloenteric duct

After lateral folding, this is the remaining communication between the gut-tube and the yolk sac/amnion vesicle

20

Pleuropericardial folds

Folding in of the tissue between the pleural cavities (where lungs will form) which are inferior and posterior to the pericardial cavity (where heart will form). They separate the former pleuroperitoneal canals from the pericardial cavity, and create the pleural space.

21

Pleuropericardial membrane, origin and what they contain

Pleuropericardial folds become these membranes. These membranes contain common cardinal veins and phrenic nerves

22

What does septum transversum become?

the central tendon of the diaphragm

23

pleuroperitoneal membrane

Originates from pleuroperitoneal folds, grows in from lateral body wall to merge with septum transversum and dorsal mesentery of esophagus. There are small openings closed by migrating myoblasts

24

Crura of diaphragm

pair of muscle bundles that originate from myoblasts that migrate into the dorsal mesentary

25

dorsal mesentary contributes what to diaphragm

Forms median part of diaphragm

26

Lateral Body wall muscular ingrowth contribution to diaphragm

Forms the peripheral edges of the diaphragm

27

Formation of costo-diaphragmatic recesses

Also called costophrenic angles, formed by descending pleural space during development

28

Innervation of diaphragm

2 phrenic nerves (motor&sensory, C3, C4, C5). Spinal nerves migrate with septum transversum, lengthen to 30 cm as diaphragm descends during development.
Intercostal nerves to the body wall (sensory)

29

Congenital Diaphragmatic Hernia

1/2200 newborns, 85% of time on left side bc that side closes later than right side; viscera herniates into thorax