Cardiovascular Embrylogy

Question 1

What effect does the embryo folding have on development of the heart?

Answer 1

Lateral fold = creates heart tube

Cephalocaudal fold = bring tube into thoracic region

Question 2

What are the 6 parts of the primitive heart tube?

Answer 2

Aortic roots 
Truncus arteriosus 
Bulbus cordis 
Ventricle 
Atrium 
Sinus venosus

Question 3

When does the heart start looping?

Answer 3

Day 23

Question 4

Why does the heart start looping?

Answer 4

Tube elongates and runs out of space

Question 5

How does the heart tube loop?

Answer 5

Bulbis cordis moves forward, down and right

Primitive ventricle moves back, up and left

Question 6

What space does the heart tube looping form?

Answer 6

Transverse pericardial sinus - arteries in front of veins

Question 7

What initially receives in flow to the primitive heart?

Answer 7

Sinus venosus - via right and left sinus horns

Question 8

How does the right atrium develop?

Answer 8

Left sinus horn receded to form coronary sinus

Right sinus horn enlarges and is absorbed into growing right atrium

Question 9

How does the left atrium develop?

Answer 9

The four pulmonary veins are incorporated into the left atrium

Question 10

What space is created by the left atrium development?

Answer 10

Oblique pericardial sinus

Question 11

How does the arterial system begin to develop?

Answer 11

Bilateral symmetrical system of arched vessels = aortic arches

Question 12

How many aortic arches are there?

Answer 12

5 - numbered 1, 2, 3, 4, 6

Question 13

What is derived from the 1st aortic arch?

Answer 13

Maxillary artery
Hyoid artery
Stapedial artery

Question 14

What is derived from the 2nd aortic arch?

Answer 14

Maxillary artery
Hyoid artery
Stapedial artery

Question 15

What is derived from the 3rd aortic arch?

Answer 15

Common carotid artery

Part of proximal internal carotid

Question 16

What is derived from the 4th aortic arch?

Answer 16

Right = subclavian artery

Left = part of aortic arch

Question 17

What is derived from the 6th aortic arch?

Answer 17

Right = R pulmonary artery

Left = L pulmonary artery + ductus arteriosus

Question 18

What nerve is associated with the 6th aortic arch?

Answer 18

Recurrent laryngeal nerve

Question 19

What happens to the right recurrent laryngeal nerve?

Answer 19

Initially hooks around 6th arch

Distal part of arch disappears

Moves up to hook around 4th arch

Question 20

What happens to the left recurrent laryngeal nerve?

Answer 20

Hooks around 6th arch

Distal part of arch persists as ductus arteriosus

Nerve remains in position

Question 21

How is the heart split into right and left channels?

Answer 21

Endocardial cushions expand and divide the heart

Question 22

How are the atria divided?

Answer 22

Septum primum grows down towards fused endocardial cushions

Ostium primum = hole before septum fuses with cushions

Before ostium primum closes, ostium secondum appears in septum primum

Crescent shaped septum secondum grows next to septum present

Hole in septum secondum = foramen ovale

Question 23

How are the ventricles divided?

Answer 23

Muscular portion of the septum grows up from floor to endocardial cushions

Small gap remains

Gap is filled by membranous portion

Question 24

How is the outflow divided?

Answer 24

Endocardial cushions in truncus arteriosus grow into spiral septum