Right atrium

Right atrium
File:Diagram of the human heart (cropped).svg
Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow.
File:Gray493.png
Interior of right side of heart.
Latin	atrium dextrum
Gray's	subject #138 528
Artery	Right coronary artery
MeSH	Right+Atrium

The right atrium (in older texts termed the "right auricle", which now means the right atrial appendage) is one of four chambers (two atria and two ventricles) in the hearts of mammals (including humans) and archosaurs (which include birds and crocodilians). It receives deoxygenated blood from the superior and inferior vena cava and the coronary sinus, and pumps it into the right ventricle through the tricuspid valve. Attached to the right atrium is the right auricular appendix.

Nodes

The sinoatrial node (SAN) is located within this chamber next to the vena cava. This is a group of pacemaker cells which spontaneously depolarize to create an action potential. The cardiac action potential then spreads across both atria causing them to contract forcing the blood they hold into their corresponding ventricles.

Embryology

In early life, when a fetus is in the womb, the right atrium has a hole within its septum through to the left atrium, this makes them continuous with each other which is essential for fetal circulation. This junction is called the “Foramen ovale." Once born (usually within 9 month's time) the foramen ovale seals over. This occurs when the first breath is taken; fetal blood flow is reversed and now travels through the lungs no longer requiring the foramen ovale. Therefore it closes and is renamed as the “Fossa ovalis.” The fossa ovalis is seen as an embryonic remnant.

In some cases, the foramen ovale fails to close and is present in 20% of the general population, however it does not cause problems in the vast majority. This is known as a patent foramen ovale.

Within the fetal right atrium, blood from the inferior vena cava and the superior vena flow in separate streams to different locations in the heart, and this has been reported to occur through the Coanda effect.

Structures of Right Atrium

1. Sinus Veranum: smooth walled portion that surrounds the opening of the superior and inferior vena cava and the coronary sinus. a.This region is the embryological remanant of venous blood vessels that were absorbed into the formation of the right atrial wall

2. Openings of three vessels: 'a.'Superior Vena Cava 'b.'Inferior Vena Cava 'c.'Coronary Sinus

3. Pectinate muscles(musculi pectinati): muscular wall of the atria

4. Right auricle: pouch-like extension of the muscular part (pectinate muscles) of the right atrium

5. Crista terminalis: a ridge separating the muscular and smooth walled parts of the right atrium

6. Interatrial septum: separates right atrium from left atrium ' a.'Fossa Ovalis, represents the closure of an opening that was present within the interatrial septum of the fetal heart (normal) and was called the foramen ovale

     i.Fossa ovalis, a depression that looks like "thumb print" within the interatrial wall

7. Tricuspid valve: Its superior surface is from the right atrium

Supply

The right atrium is supplied with oxygenated blood by the right coronary artery.

The opening of the vein that drains the myocardium itself is found on the right atrium. This is called the coronary sinus.

Additional images

• Heart right anatomy.jpg

  Heart right anatomy

References

2. Sawitzke, S. Human Gross Anatomy. Visceral Anatomy. Anatomy of the Thorax, Abdomen, Pelvis and Perineum. Revised 2004-2005. University of Bridgeport. College of Chiropractic

External links

• Anatomy Tables - Heart

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