Body Cavities

Front 1

Describe the formation of the intraembryonic coelom:
When?
Where?
what are the results?

Back 1

-appears late in thrid week within the lateral plate mesoderm
-Splits the LPM into the somatic and splanchnic mesoderm

Front 2

Formation of the intraembryonic coelom splits the lateral plate mesoderm into two layers. What are these layers and what are they associated with

Back 2

1. somatic mesoder, associated with ectoderm, before folding it is continuous with the EEM that coats the amnion
2. Splanchnic mesoderm-associates with endoderm, before folding it is continuous with the mesoderm that coats the yolk sac
**After folding the mesoderm continuities are lost**

Front 3

As the embryo grows and folds, the IEC becomes U shaped with longitudinal and transverse portions (the gut tube is in between). What do each of these portions form?

Back 3

longitudinal=pericardioperitoneal (pleural) canals
transverse=primitive pericardial cavity

Front 4

The primitive pericardial cavity is the transverse portion of the U shaped IEC. Describe how the spatial relationship of this cavity changes as a result of cranial-caudal embryo folding.

Back 4

brings the primitive pericardial cavity to the ventral side of the body and cranial to the septum transversum, it tucks the heart up and in placing the future heart cavity median and ventral to the pleural cavities

Front 5

Folding in which plane ends the communication of the IEC with the EEC

Back 5

this communication is lost when the ventral body wall forms during embryo folding in the horizontal plane, note that cranial-caudaul folding is also important for this "seal" (purse-string analogy)

Front 6

Describe the formation of the Serous membranes within the IEC

Back 6

-the somatic mesoderm forms the parietal layer which will become the parietal pleura and the parietal peritoneum
-the splanchnic mesoderm will form the visceral layer that becomes the visceral pleura and visceral peritoneum
-the two layers are continuous at the dorsal mesentary and the hilum of the lung

Front 7

Erros in which folding direction are most likely to be involved with ventral body wall defects?

Back 7

lateral folding
problem can be insufficient migration of folds, fusion probelm, or re-rupture

Front 8

T/F omphalocele is caused by a failure of ventral body wall closure

Back 8

false, this is a failure of the midgut to retract back into the abdomen, it is not associated with a failure of the wall to close

Front 9

Where is the cardiogenic cresecent

Back 9

It is part of the primitive pericardial cavity which is the transverse portion of the U shpaed IEC
The cresent lies within the splanchnic mesoderm forming the medial wall of the primitive pericardial cavity.

Front 10

At first, the primitive pericardial cavity is continous with the pericardioperitoneal canals (the U is a continous loop). How are the two cavities separated?

Back 10

-Lung buds grow laterally from the respiratory diverticulum (outgrowth of foregut)
-this growth puses out pericardioperitoneal folds which begin to separate the two cavities
-The folds eventually fuse with the mesenchyme ventral to the foregut to form a complete partition
-the mesenchyme of the pleuropericardial folds becomes the fibrous and serous layers of the parietal pericardium

Front 11

Explain how the pericardial cavity is separated from the IEC

Back 11

-lung buds growing from RD of the foregut push into the body wall
-the pushing forms the pleuropericardial folds which continue to extend and grow into membranes, heart looping also contributes to this growth
-the edges of the folds eventually fuse wit hmesenchyme ventral to the foregut forming a complete partition between the pericardial cavity and the plueral cavity

Front 12

What does the mesenchyme of the pleuropericardial folds eventually become?

Back 12

The fibrous and serous layers of the parietal pericardium

Front 13

Explain how the phrenic nerve reaches its location in the adult.

Back 13

2 reasons: growth of lungs and descent of septum transversum.
descent of the septum transversum brings the nerve down into the thorax
The growth of the pleuralpericardial folds brings it to the midline from near the body wall.
This explains why, in the adult, the phrenic nerve lies on the fiberous pericardium

Front 14

Explain how the pleural cavity is formed

Back 14

-Process is similar to formation of pericardial cavity
-As the lungs grow, they push out pleuroperitonlea folds that eventually grow into pleuroperitoneal membranes
-the pleuroperitoneal membranes fuse with the mesentary dorsal to the forming esophagus closing the connection between the pleural cavities and the abdominal cavity

Front 15

How are the costodiaphragmatic recesses formed?

Back 15

The lungs continue to expand into the body wall enlarging the pleural cavities

Front 16

What are the 3 primorida that merge to form the diaphragm

Back 16

1. septum transversum
2. dorsal mesentery of the esophagus
3. pleuroperitoneal folds
(remember, the pleuroperitoneal folds fused with the dorsal mesentary in order to complete the formation of the pleural cavity)

Front 17

what are the pericardioperitoneal canals?
how are they closed?

Back 17

these are the longitudinal poritons of the U shaped IEC. They are connection between the thoracic and abdominal cavity. The canals are closed by the formation of the pleural cavity via the pleuroperitoneal folds and formation of the diaphgram when the folds fuse with the dorsal mesentery of the esophagus and the septum transversum

Front 18

Explain how the muscular portion of the diaphragm is formed

Back 18

As the lungs and pleural cavitiy continue to grow, they "burrow" into the body wall splitting the body wall into two layers. The mesenchyme from this area forms a rim around the pleuroperitoneal membranes which is invaded by myoblasts. The myoblasts then continue to invade the mebranes and continue to make muscle.

Front 19

The precursors of the diaphragm are the pleuroperitoneal membranes, the septum transversum, and the mesentary dorsal to the esophagus. What structure do each of these become in the adult?

Back 19

septum transversum=central tendon
crura= dorsal mesentary
folds= muscular portion

Front 20

what is the cause of a congenital diaphragmic hernia resulting from a posterolateral defect?
aka foramen of Bochdalek

Back 20

incomplete formation/fusion of the pleuroperitoneal membrane with the septum transversum

Front 21

When is a congenital diaphragmaic hernia most likely to occur

Back 21

If a defect in the diaphragm is present, the GI conetents can herniate into the thorax as they return to the abdomen around week 10

Front 22

In addition to herniated guts, what problems can a congenital diaphgramic hernia cause

Back 22

the guts take up sapce in the thorax leading to pulomonary hypoplasia resulting in persisetent pulmonary hypertension. The heart and mediasinum are often shifted to the right (the hernia usually ocurs on the left) and the abdomen becomes narrow and sunken (scaphoid abdomen),
polyhydramios is often associated w/ CHD