Embryology

Question 1

What is the CV system originate from?

Answer 1

splanchnic mesoderm

Question 2

What are the 5 portions of the primitive heart?

Answer 2

truncus arteriosus
Bulbus cordis
ventricle
atrium
sinus venosus

Question 3

What does the truncus arteriosus become?

Answer 3

pulmonary artery and aorta

Question 4

What does the bulbus cordis become?

Answer 4

the right ventricle

Question 5

What is the sinus venosus?

Answer 5

paired region into which the veins drain

Question 6

What does the left sinus venosus become?

Answer 6

the coronary sinus

Question 7

What does the right sinus venosus become?

Answer 7

it becomes incorporated into the right atrial wall

Question 8

After formation of an endocardial tube - what occurs in development of the heart?

Answer 8

Forms an s-shaped curve

Truncus arteriosus –> bulbus cordis –> ventricle –> common AV opening –> atrium –> sinus venosus

Question 9

What is the function of the truncus arteriosus in the embryonic heart?

Answer 9

common outflow tract

Question 10

What is the function of the sinus venosus in the embryonic heart?

Answer 10

receives venous blood into the heart

Question 11

How does the common atrioventricular become partitioned?

Answer 11

proliferation of the endocardial cushion and migration ventrally

Will eventually sit in the common area between the atria and ventricles

Question 12

How are the atria partitioned?

Answer 12

Two separate septa are formed from dorsal atrial wall ventrally: septum primum and secundum - that grow to meet the endocardial cushion

Question 13

What is the foramen primum? secundum?

Answer 13

Septum primum grows from dorsal atrial wall, obliterates pre-existing foramen primum

Foramen secundum develops through fenestrations of the first septum (dorsally within the atria)

Question 14

What is the foramen ovale?

Answer 14

After the septum secundum grows ventrally (over top of the foramen secundum) - it will remain incomplete and the free edge forms the foramen ovale

Question 15

What are the three stages of the interatrial foramen in the embryonic heart?

Answer 15

foramen primum
foramen secundum
foramen ovale

Question 16

How are the embryonic ventricles partitioned?

Answer 16

Ventral –> dorsal growth of a muscular ridge from the central region of the common ventricle

Question 17

How are the aorta and pulmonary trunk formed?

Answer 17

Truncus arteriosus partitioned in a spiral pattern to form the aorta and pulmonary trunk

Question 18

What deformity occurs if the truncus arteriosus fails to develop?

Answer 18

Transposition of the great vessels: Aorta will remain connected to the right ventricle, and the pulmonary trunk to the left ventricle

Question 19

What does the paired ventral aorta become?

Answer 19

brachiocephalic trunk

Question 20

Which of the aortic arches regress without forming anything?

Answer 20

1, 2 and 5

Question 21

Which of the aortic arches will become a important structure?

Answer 21

3, 4 and 6

Question 22

What does the third aortic arch become?

Answer 22

Internal carotid artery and common carotid artery

External carotid artery buds from the third arch

Question 23

What does the left fourth aortic arch become?

Answer 23

Arch of the aorta

Question 24

What does the fourth right arch of the aorta become?

Answer 24

the right subclavian artery

Question 25

What do the sixth embryonic aortic arches become?

Answer 25

pulmonary arteries | Right - ductus arteriosus

Question 26

What is the purpose of the ductus arteriosus?

Answer 26

shunts blood from the pulmonary system into systemic circulation

Question 27

What is the persistence of the ductus arteriosus called after birth?

Answer 27

PDA

Question 28

Why does a PDA result in continuous shunting?

Answer 28

the aorta pressure is higher than the pulmonary artery in all stages --> continuous shunting into the pulmonary vasculature system.

Question 29

What are the major embryonic veins?

Answer 29

``` Sinus venosus vitelline veins umbilical veins common cardinal veins cranial cardinal veins caudal cardinal veins: super and supracardinal veins ```

Question 30

What embryonic veins will form the cranial vena cava and its major cranial branches (jugular)?

Answer 30

Each cranial cardinal will form the internal jugular vein External jugular and subclavian veins bud from cranial cardinal veins Caudal segment of right cranial cardinal vein and right common cardinal vein become right cranial vena cava

Question 31

What forms the brachiocephalic vein? What does this vessel do? If this does not form appropriately - what congenital vascular abnormality occurs?

Answer 31

left cranial cardinal vein Shunts venous blood from the left --> right into the CrVC double cranial vena cava

Question 32

What embryonic vasculature forms the cranial portion of the caudal vena cava?

Answer 32

Right subcardinal and right vitelline vein

Question 33

What embryonic vasculature forms the caudal portion of the caudal vena cava?

Answer 33

supracardinal vein

Question 34

What embryonic vessel becomes the azygos vein?

Answer 34

supracardinal vein, caudal and common cardinal veins of right side

Question 35

What embryonic vessel becomes the portal vessel?

Answer 35

vitelline vein

Question 36

What embryonic vessel forms the ductus venosus?

Answer 36

umbilical vein

Question 37

How can portosystemic shunts form?

Answer 37

Persistent ductus venosus | Anastomosis between portal vein and CVC or azygos (not too unreasonable given all the patchwork that goes on).

Question 38

Describe the major components of the fetal circulation?

Answer 38

Fetal CO2 is exchanged for maternal oxygen at the placent --> umbilical veins --> fetus --> ductus venosus (shunts blood from liver tot he heart) --> shunts that prevent blood from entering pulmonary circulation (foramen ovale, ductus arteriosus) --> aorta --> extremities, body --> umbilical arteries

Question 39

How does a double aortic arch form?

Answer 39

Persistence of both dorsal aortic arches | Considered a type 4 vascular anomaly

Question 40

What is the most common form of VRA?

Answer 40

PRAA - retention of 4th aortic arch - rather than the left 4th aortic arch forming the main aortic arch - the right will

Question 41

How does an aberrant right subclavian form?

Answer 41

Bi-subclavian trunk - both subclavians have a common origin on the aberrant right aortic arch- the left has to cross over to reach the left side.