Development of the Heart and Great Vessels

Question 1

What are the three layers of the mesoderm?

Answer 1

1. Paraxial mesoderm
2. Intermediate mesoderm
3. Lateral plate mesoderm

Question 2

What are the two layers of the lateral plate mesoderm?

Answer 2

• Somatic layer (lines body cavities)

- Splanchnic/Visceral mesoderm (covers organs)

Question 3

What do angiogenic cells form?

Answer 3

Blood islands

Question 4

What is the endocardial tube covered by?

Answer 4

Cardiac Jelly

Question 5

What does the intraembryonic coelom give rise to?

Answer 5

• Pericardial cavity
• Pleural cavity
• Peritoneal cavity

Question 6

Which side of the endocardial tube is rich in blood?

Answer 6

The venous end

Question 7

What are the 3 pairs of veins called that the sinus venosus receives?

Answer 7

• Cardinal veins
• Viteline veins
• Umbilical veins

Question 8

What vein drains the venous blood of the yolk sac?

Answer 8

The viteline vein

Question 9

What vein drains the blood of the body wall of the foetus?

Answer 9

The cardinal vein

Question 10

Name the parts of the heart (endocardial) tube from inferior to superior

Answer 10

• Sinus venosus
• Primordial atrium
• Primordial ventricle
• Bulbus cordis
• Aortic sac

Question 11

What parts of the endocardial tube move anteriorly?

Answer 11

Bulbus cordis and Primordial ventricle

Question 12

What day does the heart start to beat?

Answer 12

Day 22

Question 13

What structures are carved out of the cardiac jelly?

Answer 13

• The heart valves
• Papillary muscles
• Chordae tendinae
• IV septum

Question 14

What does the primordial ventricle develop into?

Answer 14

The left ventricle

Question 15

What does the proximal segement of the bulbus cordis develop into?

Answer 15

Right ventricle

Question 16

What is the gap between the endocardial cushion and septum primum called?

Answer 16

Ostium primum

Question 17

When does the ostium primum close?

Answer 17

When the ostium secundum develops

Question 18

What kind of surface is on the inside of the Sinus Venosus?

Answer 18

Smooth

Question 19

What forms the septum secundum?

Answer 19

The wall of the sinus venosus which invaginates into the primordial atrium

Question 20

What does the ostium secundum become?

Answer 20

The falx septi

Question 21

What lies more superiorly the foramen ovale or falx septi?

Answer 21

The falx septi

Question 22

Where does the foramen ovale lie?

Answer 22

In the septum secundum

Question 23

Where does the septum secundum lie?

Answer 23

• In the primordial atrium

- To the right of the septum primum

Question 24

What does the truncus arteriosus (conus cordis) develop into?

Answer 24

Aorta and pulmonary trunk

Question 25

What does the 7th intersegmental artery grow towards?

Answer 25

The upper limb (become subclavian arteries)

Question 26

Bridge like anastomostic artery of first to seventh segemental arteries becomes what?

Answer 26

Vertebral arteries

Question 27

What do the 3rd aa arteries become?

Answer 27

The carotid arteries

Question 28

What do the vertebral arteries form to become?

Answer 28

The basilar artery

Question 29

What does the 6th aortic arch become?

Answer 29

The pulmonary artery

Question 30

What are the intercostal arteries derivatives of?

Answer 30

The thoracic intersegmental arteries

Question 31

How can the bulbus cordis divided?

Answer 31

- Proximal 1/3 - Middle 1/3 (conus cordis) - Distal 1/3 (Truncus arteriosus)

Question 32

What does the primordial atrium develop into in adults?

Answer 32

Right and left auricles

Question 33

What does the middle 1/3 of the bulbus cordis develop into (aka Conus cordis)?

Answer 33

Infundibulum (RV) and aortic vestibule (LV)

Question 34

What does the distal bulbus cordis (aka Truncus arteriosus) develop into?

Answer 34

Roots and proximal part of pulmonary trunk and aorta

Question 35

What does the left subclavian artery derive from?

Answer 35

The 7th intersegmental artery

Question 36

What does the right subclavian artery derive from?

Answer 36

The 4th aortic arch (proximal), dorsal aorta and 7th intersegmental artery

Question 37

What is patent foramen ovale caused by?

Answer 37

Defect on septum secundum. Can be caused by ostium secundum not closing

Question 38

What is an atrial septal defect caused by?

Answer 38

Failure of proper development of septum secundum or failure of closure of ostium primum

Question 39

What is a ventricular septal defect caused by?

Answer 39

Caused by either a defect in membranous (endocardial cushion) (more common) or muscular portion of IV septum (primordial ventricle + BC)

Question 40

What is tetralogy of Fallot caused by?

Answer 40

Caused by an unequal division of conus cordis with resultant anterior displacement (malaignment) of the aorticopulmonary septum.

Question 41

What is Transposition of the great vessels caused by?

Answer 41

Caused by failure of the aorticopulmonary (conotruncal) septum to spiral

Question 42

What is the possible cause of coarctation of the aorta?

Answer 42

Contraction of ductus arteriosus

Question 43

When does cephalo-caudal and lateral folding begin?

Answer 43

Towards the end of the 3rd week i.e at about 18 days

Question 44

What are the endocardial cushions derived from?

Answer 44

Neural crest cells

Question 45

What does enlargement of endocardial cushions form?

Answer 45

- Interatrial septum - Membranous part of IV septum - AV valves (tricuspid and mitral) - Formation of the PT and aorta from the truncus arteriosus

Question 46

What structure causes the left recurrent laryngeal to stay in the thorax?

Answer 46

The ductus arteriosus Both L and R wrap around the 6th arch but this regresses in the R but not the L where the ductus arteriosus keeps the L in the thorax, this then disapates and subsequently the L wraps around the aortic arch. While the R wraps around the 4th aa on the right side (R subclavian artery)