Difference Between Sinus Venosus and Conus Arteriosus

The key difference between sinus venosus and conus arteriosus is that sinus venosus is a big quadrangular cavity that precedes the right atrium on the venous side of the chordate heart, while conus arteriosus is a conical pouch that is formed from the upper and left angle of the right ventricle in the chordate heart.

Sinus venous is an early developmental cardiovascular structure. It is a thin-walled cavity. This cavity forms the input to the developing heart, which has 3 venous inputs: vitelline vein, umbilical vein, common cardinal vein. Later in the heart development, this cavity gets incorporated into the wall of the future right atrium. Conus arteriosus is a smooth-walled pouch of the right ventricle directly below the pulmonary valve. Defect in conus arteriosus can cause problems in the heart.

CONTENTS

1. Overview and Key Difference
2. What is Sinus Venosus
3. What is Conus Arteriosus
4. Similarities Between Sinus Venosus and Conus Arteriosus
5. Side by Side Comparison – Sinus Venosus vs Conus Arteriosus in Tabular Form
6. Summary

What is Sinus Venosus?

Sinus venosus is a large quadrangular cavity that precedes the right atrium located in the chordate heart. In mammals, it is in the heart of the embryonic development stage. In adults, it is incorporated into the wall of the right atrium to form a smooth part called the sinus venarum. It is separated from the rest of the atrium by a ridge of fibres called “crista terminalis”. In mammals, sinus venosus forms the SA node and the coronary sinus.

In the embryonic development stage, the thin walls of the sinus venosus are connected below with the right ventricle and medially with the left atrium. Sinus venosus receives blood from three venous inputs; vitelline vein, umbilical vein, and common cardinal vein. It typically starts as a paired structure. As the embryonic heart develops, sinus venosus shifts towards associating only with the right atrium. The left portion of the sinus venosus shrinks in size and forms the coronary sinus (right atrium) and oblique vein of the left atrium. The right part becomes integrated into the right atrium to form the sinus venarum.

What is Conus Arteriosus?

Conus arteriosus is a conical pouch developed from the upper and left angle of the right ventricle in the chordate heart. It is also known as the infundibulum. The pulmonary trunk also arises from this region. Conus arteriosus develops from the bulbus cordis. Bulbus cordis is a part of the developing heart. Normally, the infundibulum refers to the corresponding internal structure, while the conus arteriosus refers to the external structure.

The defects in conus arteriosus development can result in a severe heart condition known as tetralogy of Fallot. A tendinous band connects the posterior of the conus arteriosus to the aorta. The wall of the conus arteriosus is smooth. The conus arteriosus is the entrance from the right ventricle into the pulmonary artery and pulmonary trunk.

What are the Similarities Between Sinus Venosus and Conus Arteriosus?

• Sinus Venosus and Conus Arteriosus are two parts of the chordate heart. Their defects cause dangerous heart conditions.
• Both contain deoxygenated blood.

What is the Difference Between Sinus Venosus and Conus Arteriosus?

Sinus venosus is a large quadrangular cavity that precedes the right atrium on the venous side of the chordate heart. On the other hand, conus arteriosus is a conical pouch that is developed from the upper and left angle of the right ventricle in the chordate heart. Thus, this is the key difference between sinus venosus and conus arteriosus. Sinus venosus is a large quadrangular cavity, while conus arteriosus is a conical pouch.

The below infographic lists the differences between sinus venosus and conus arteriosus in tabular form.

Summary – Sinus Venosus vs Conus Arteriosus

Sinus venosus is a large quadrangular cavity that precedes the right atrium in the chordate heart. The sinus venosus develops into the posterior portion of the right atrium. It also forms the SA node and the coronary sinus. The conus arteriosus is a conical pouch formed from the upper and left angle of the right ventricle. The pulmonary artery also arises from this region. Thus, this is the summary of the difference between sinus venosus and conus arteriosus.

Reference:

1. “Sinus Venosus.” An Overview | ScienceDirect Topics, Available here.
2. “Conus Arteriosus.” Wikidoc, Available here.

Image Courtesy:

1. “P3a_002_coeur sinus veineux oreillette_heart sinus venosus atrium_Scyliorhinus canicula” By Franck Genten (CC BY-NC-ND 2.0) via Flickr

2. “Gray492” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 492 (Public Domain) via Commons Wikimedia