diaphragm embryology

Question 1

what type of septum is the diaphragm ? and its function ?

Answer 1

dome shaped, musculo-tendinous septum
separates thoracic cavity from abdominal cavity & primary muscle of respiration

Question 2

several opening of the diaphragm and their associated levels ?

Answer 2

• caval opening/hiatus (vena caval foramen) , IVC - T8
• oesophageal hiatus - T10
• aortic hiatus - T12

Question 3

4 structures that diaphragm is derived from ?

Answer 3

• septum transversum - central tendon
• pleuroperitoneal membrane - muscular part
• peripheral margin - peripheral muscular part
• dorsal esophageal mesentery - crura of diaphragm

Question 4

what gives rise to the crura of the diaphragm ?

Answer 4

mesentery of the oesophagus

Question 5

what is the crura ?

Answer 5

stout(fat) columns of muscle tissue that anchor the diaphragm to the lumbar vertebral column posteriorly

Question 6

which hiatus is within the following ?
1. right crus of diaphragm
2. right and left crura of diaphragm

Answer 6

1. oesophageal
2. (abdominal) aortic

Question 7

what happens week 4-5 in development of diaphragm ?

Answer 7

• Septum transversum grows and forms “pericardio-peritoneal” diaphragm
• Diaphragm descends from C3-C5 towards thorax
• Phrenic nerve descends along with the diaphragm

Question 8

what happens week 5-8 in development of diaphragm ?

Answer 8

• Pleuroperitoneal membranes close and form “pleuro-peritoneal” diaphragm
• Diaphragm descends to L1

Question 9

what happens week 9-12 in development of diaphragm ?

Answer 9

• Lateral body wall mesenchyme forms additional rim around “pleuro-peritoneal” diaphragm
• This peripheral rim derives innervation from lower intercostal nerves

Question 10

the septum transversum begins to condense from .1… during week ..2.. of development

Answer 10

1. mesoderm
2. 3

Question 11

Where does the septum transversum :
1. appear ?
2. is innervated by ?

Answer 11

1. in cervical region
2. cervical spinal nerves

Question 12

Why does the phrenic nerve (C3-5) supply the diaphragm ?

Answer 12

as the embryo folds during week 4, the septum transversum is displaced caudally in the embryo but carries its original nerve supply with it

Question 13

What are at the sides of the septum transversum ? what do they do ?

Answer 13

pericardioperitoneal canals - connect the developing thoracic cavity with the developing peritoneal cavity

Question 14

what later closes the pericardioperitoneal canals ?

Answer 14

growth of the pleuroperitoneal membranes

Question 15

between weeks 5 and 7 what happens resulting in the closing of the pericardioperitoneal canals ?

Answer 15

pair of horizonal pleuroperitoneal membranes grow from the posterior body wall to meet the septum transversum

Question 16

by week 7 what has happened for the development of the diaphragm ?

Answer 16

the pleuroperitoneal membranes have closed the pericardioperitoneal canals effectively separating the thoracic cavity from the abdominal cavity

Question 17

By the ..1.. of development , ..2.. from the body wall have ..3… the diagphragm to complete its …4.. development

Answer 17

1. 4th month
2. myoblasts
3. grown into
4. muscular

Question 18

name an abnormalitiy associated with development of diaphragm

Answer 18

congenital diaphragmatic hernia (CDH)

Question 19

congenital diaphragmatic hernia (CDH) = defect of the diaphragm that …?

Answer 19

allows passage of abdominal viscera into the thorax

Question 20

what is the most common congenital diaphragmatic hernias ?

Answer 20

posterolateral or bochdalek hernia or pleuroperitoneal

Question 21

what does posterolateral or bochdalek hernia or pleuroperitoneal result from ?

all 3 refer to same thing of CDH

Answer 21

failure of the pleuroperitoneal membranes to develop and close the pericardioperitoneal canals

Question 22

what are the 2 main complications and causes of mortality of congenital diaphragmatic hernia ?

Answer 22

• pulmonary hypoplasia
• pulmonary hypertension

Question 23

Treatment of CDH in utero ?

Answer 23

fetoscopic endoluminal tracheal occlusion (FETO)

Question 24

what is FETO as a treatment for CDH ?

Answer 24

fetoscopic endoluminal tracheal occlusion (FETO)

• blocking of trachea to stop fluid produced by foetal lungs escape into the amniotic fluid
• lung fluid expands the lungs, stimulates their growth, pushes abdominal contents out of chest into abdomen

Question 25

What are the after-birth surgical repair of CDH ?

Answer 25

i. Primary repair (small opening in the diaphragm)
ii. Patch repair (larger opening)
iii. Muscle flap repair (the hole is closed with a flap of muscle)