Embryology - Thorax

Question 1

What are the five regions the primitive heart tube (paired endothelial tubes) develops into?

Answer 1

Sinus venosus
Atrium
Ventricle
Bulbus cordis
Truncus arteriosus

Question 2

Which of the five regions of the primitive heart tube becomes incorporated into the atria and ventricle?

Answer 2

Sinus venosus (atrium)
Bulbus cordis (ventricle)

Question 3

Which two septal ‘defects’ contribute to the valve-like Foramen Ovale?

Answer 3

Foramen secundum, overlapped on the right by the septum secundum

Question 4

How does the foramen ovale function?

Answer 4

The septum secundum provides a free edge, acting like a valve, allowing blood to flow from right to left

Question 5

In normal development, what causes the foramen ovale to close?

Answer 5

Increased blood flow through the pulmonary circuit leads to raised left atrial pressure which pushes the septum primum against the foramen ovale

Question 6

What is the fossa ovalis?

Answer 6

Fusion of the septum primum and secundum and obliteration of the foramen ovale, leading to a small dimple