Embryology

Question 1

What germ layer does the cardiac tissue develop from?

Answer 1

cardiogenic mesoderm at the cranial end of the embryo

Question 2

Where do the cardiac cells come from?

Answer 2

the cells come from the myoblasts and blood islands in a horseshoe shape around neural plate

Question 3

Where are the blood islands?

Answer 3

are within the mesoderms so are covered in ectoderm

Question 4

What does lateral folding achieve?

Answer 4

brings the two edges of the horseshoes together to create the heart tube

Question 5

What does cranial-caudal folding achieve?

Answer 5

moves the heart downwards

Question 6

When is looping complete?

Answer 6

day 28

Question 7

What are the five main regions of the heart tube?

Answer 7

Truncus arteriosus
Bulbus cordis
Ventricular
Atrial
Sinus venosus

Question 8

What does the truncus arteriosus give rise to?

Answer 8

aorta and pulmonary trunk

Question 9

What does the bulbus cordis give rise to?

Answer 9

trabeculated part of right ventricle and outflow part of both ventricles

Question 10

What does the ventricular section give rise to?

Answer 10

trabeculated part of left ventricle

Question 11

What does the atrial section give rise to?

Answer 11

trabeculated part of both atria

Question 12

What does the sinus venosus give rise to?

Answer 12

smooth part of right atrium and coronary sinus

Question 13

Where does blood move from in the embryo?

Answer 13

caudal to cranial so sinus venosus to truncus arteriosus

Question 14

When does folding and looping start?

Answer 14

day 23

Question 15

What are the main movement that occur in looping and folding?

Answer 15

Atrium moves dorsally and cranially
Ventricle is displaced left
Bulbus cordis is moved inferiorly and ventrally to the right
The sinus venosus and the primitive atria move dorsally
The primitive ventricle and outflow tracts move ventrally

Question 16

When does ventricular septation begin?

Answer 16

day 25

Question 17

Where does the interventricular sputum develop from and to?

Answer 17

from between the left ventricle and the bulbus cordis towards the endocardial cushions

Question 18

Where does the truncoconal septum extend?

Answer 18

inferiorly into the ventricular septum

Question 19

What three septal structures fuse in the 7th week?

Answer 19

• primary muscular septum
• truncoconal septum
• atrioventricular endocardial cushions

Question 20

When does atrioventircular septation start?

Answer 20

day 26

Question 21

What completes the septation of the atrioventricular canal?

Answer 21

endocardial cushions

Question 22

What descends at day 30?

Answer 22

septum primum from roof of atrium to the endocardial cushions

Question 23

Where is the foramen ovale?

Answer 23

septum secundum

Question 24

Where do the aortic arches form?

Answer 24

high in the cervical region

Question 25

What does aortic arch 3 form into?

Answer 25

common carotid arteries and the first part of the internal carotid artery

Question 26

What does aortic arch 4 form into?

Answer 26

right subclavian artery and on the left is part of the aortic arch

Question 27

What does aortic arch 6 form into?

Answer 27

sprout branches that form pulmonary arteries on both sides and ductus arteriosus on left

Question 28

What are the vessels coming into the sinus venosus?

Answer 28

- cardinal vein (head and body) - umbilical vein (supplies blood from placenta) - vitelline vein (drains yolk sac but develops into haptic and portal mesenteric arteries)

Question 29

What happens to the right and left horn?

Answer 29

right horn becomes enlarged and swollen and the left side becomes smaller

Question 30

What is the venous origin of the smooth parts of the right and left atria?

Answer 30

sinus venosus

Question 31

What are the three venous systems found in the embryo?

Answer 31

Vitelline veins Umbilical veins Cardinal veins

Question 32

What do the vitelline veins do?

Answer 32

drain yolk sac and develops into portal venous system draining gut, hepatic sinusoids and veins, hepatic portion of IVC

Question 33

What do the umbilical veins do?

Answer 33

bring oxygenated blood from the placenta and the right degenerates, left remains as definitive umbilical vein

Question 34

What do the cardinal veins do?

Answer 34

give systemic venous system and drain the head and body

Question 35

What do the anterior cardinal veins do and what do they include?

Answer 35

drain head and neck - jugular system - left brachiocephalic veins - SVC

Question 36

What do the posterior cardinal veins do and what do they include?

Answer 36

drain the trunk - azygous and hemiazygous systems - gonadal and renal veins - iliac veins - IVC