Heart: Embryological Origin | Development Of Sinus Venosus

Summary

In this lecture section, we explore the development of the sinus venosus and its embryological origins. The discussion covers the direction of blood flow through the sinus venosus, the formation of the left and right sinus horns, and their contributions to adult heart structures. It also addresses the fates of the left and right venous valves, highlighting the processes of shunting and the eventual formation of important structures like the coronary sinus and the smooth-walled right atrium. The lecture offers a detailed look at the developmental changes crucial to understanding heart formation.

Takeaways

• 😀 The heart tube and embryological development of the sinus venosus are key topics of this lecture.
• 😀 The flow of blood through the sinus venosus changes throughout development, particularly with left-to-right shunting.
• 😀 The sinus venosus receives blood from three main sources: vitelline veins, umbilical veins, and common cardinal veins.
• 😀 The sinus venosus initially communicates with the atrium, and this communication moves to the right due to blood shunting.
• 😀 The left sinus horn's role diminishes over time, and by the 10th week of development, only the left umbilical vein remains functional.
• 😀 The left sinus horn contributes to adult structures such as the coronary sinus and the oblique vein of the left atrium.
• 😀 The right sinus horn enlarges due to blood shunting and forms the smooth-walled part of the right atrium.
• 😀 The sinoatrial orifice, formed by the right sinus horn, is flanked by the right and left venous valves.
• 😀 The left venous valve is incorporated into the right atrium as the right sinus horn forms the right atrium.
• 😀 The right venous valve's superior portion disappears, while its inferior portion forms the valve of the inferior vena cava and the coronary sinus.
• 😀 The crista terminalis marks the dividing line between the trabeculated and smooth parts of the right atrium.

Q & A

What is the primary focus of this lecture?

The primary focus of the lecture is on the development of the sinus venosus and its embryological origin, including blood flow through the sinus venosus, the roles and origins of the left and right sinus horns, and the fate of the left and right venous valves.

What structures does the sinus venosus receive blood from during development?

The sinus venosus receives blood from three main sources during development: the vitelline veins, the umbilical veins, and the common cardinal veins.

How are the right and left sinus horns formed?

The right sinus horn is formed by the union of the vitelline vein, umbilical vein, and common cardinal vein, while the left sinus horn is formed by the combination of the left vitelline vein, left umbilical vein, and left common cardinal vein.

What happens to the left sinus horn by the 10th week of development?

By the 10th week of development, the left sinus horn loses its functional significance. The left common cardinal vein obliterates, leaving only the left umbilical vein, which forms adult structures such as the oblique vein of the left atrium and the coronary sinus.

What is the result of shunting blood from the left atrium to the right atrium?

Shunting of blood from the left atrium to the right atrium causes the opening of the sinus venosus to shift toward the right side during development.

What is the role of the right sinus horn in the development of the right atrium?

The right sinus horn enlarges due to the shunting of blood from the left side, and it forms the smooth-walled part of the right atrium.

What is the sinoatrial orifice, and what does it connect?

The sinoatrial orifice is a circular opening in the right atrium that connects the right sinus horn to the atrium. It is flanked by the right and left venous valves.

What happens to the left and right venous valves during development?

The left venous valve becomes incorporated into the right atrium as the right sinus horn develops. The right venous valve disappears in its superior portion, and its inferior portion contributes to the formation of the valves of the inferior vena cava and the coronary sinus.

What is the crista terminalis, and what role does it play in the right atrium?

The crista terminalis is a structure that forms a dividing line between the trabeculated part and the smooth-walled part of the right atrium, marking the boundary between these two regions.

What are the clinical correlates associated with the development of the heart as discussed in the lecture?

The lecture briefly mentions the clinical correlates of heart development, but specific details are not provided. However, these could include congenital heart defects and abnormal development of the sinus venosus or its components.