The Cardiovascular system - the right atrium

Question 1

Where does the right atrium receive blood from?

Answer 1

The right atrium receives deoxygenated blood from the superior and inferior vena cavae, and from the coronary veins.

Question 2

Where does the right atrium pump blood?

Answer 2

It pumps this blood through the right atrioventricular orifice (guarded by the tricuspid valve) into the right ventricle

Question 3

What is the right auricle?

Answer 3

The right auricle (right atrial appendage) – a muscular pouch that acts to increase the capacity of the atrium.

Question 4

What are the two surfaces of the right atrium?

Answer 4

The interior surface of the right atrium can be divided into two parts, each with a distinct embryological origin. These two parts are separated by a muscular ridge called the crista terminalis:

• Sinus venarum – located posterior to the crista terminalis. This part receives blood from the superior and inferior vena cavae. It has smooth walls and is derived from the embryonic sinus venosus.
• Atrium proper – located anterior to the crista terminalis, and includes the right auricle. It is derived from the primitive atrium, and has rough, muscular walls formed by pectinate muscles.

Question 5

Where does the coronary sinus receive blood from?

Where does it deliver blood to?

Answer 5

The coronary sinus receives blood from the coronary veins. It opens into the right atrium between the inferior vena cava orifice and the right atrioventricular orifice.