EMBRYOLOGY - Foetal Heart

Question 1

What are the two original chambers of the foetal heart?

Answer 1

Primitive atrium
Primitive ventricle

Question 2

Describe the formation of the four chambered heart during embryonic development

Answer 2

1. The interarterial and interventricular septum begin to form
2. The atrioventricular canal between the primitive atrium and ventricle begins to divide to form right and left atrioventricular ostia
3. Interventricular septum continues to form, closing the interventricular foramen to separate the right and left ventricles
4. Interartrial septum continues to form however does not fully close, allowing intercommunication between the right and left atria via the foramen ovale
5. Right and left atrioventricular (tricuspid and mitral) valves form from the atrioventricular ostia

Question 3

What are the three adaptations found in foetal circulation?

Answer 3

Ductus venosus
Foramen ovale
Ductus arteriosus

Question 4

What is the function of the ductus venosus?

Answer 4

The ductus venosus is a shunt which allows oxygenated blood from the umbilical vein to bypass the foetal liver and enter the right atrium via the caudal vena cava

Question 5

What is the function of the foramen ovale?

Answer 5

Oxygenated blood enters the right atrium and passes through the foramen ovale into the left atrium followed by the left ventricle and into the aorta to enter the foetal systemic circulation and distribute to the tissues

Question 6

What is the function of the ductus arteriosus?

Answer 6

Oxygenated blood enters the right atrium and should pass into the left atrium through the foramen ovale, however, if blood does enter the right ventricle and travel into the pulmonary trunk, the ductus arteriosus will shunt the blood from the pulmonary trunk into the aorta so it doesn’t travel to the non-functional lungs and instead travels to the placenta for oxygenation

Question 7

Describe the embryonic development of the aortic arches

Answer 7

During early embryonic development, the embryo has a left and right primitive aorta which fuse ventrally to form the aortic sac which gives rise to six symmetrical pairs of aortic arches

Question 8

Which arteries are formed from the third aortic arch in embryonic development?

Answer 8

Internal carotid arteries

Question 9

Which artery is formed from the left fourth aortic arch in embryonic development?

Answer 9

Aorta

Question 10

Which artery is formed from the right fourth aortic arch in embryonic development?

Answer 10

Right subclavian artery

Question 11

Which structure is formed from the left sixth aortic arch in embryonic development?

Answer 11

Ductus arteriosus

Question 12

Which arteries are formed from the right sixth aortic arch in embryonic development?

Answer 12

Pulmonary trunk