The pectinate muscles (musculi pectinati) are parallel muscular ridges in the walls of the atria of the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

Structure

Behind the crest (

crista terminalis The crista terminalis (also known as the terminal crest, or crista terminalis of His) is a vertical ridge on the posterolateral inner surface of the adult right atrium extending between the superior vena cava, and the inferior vena cava. The cris ...

) of the

right atrium The atrium (; : atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ...

the internal surface is smooth. Pectinate muscles make up the part of the wall in front of this, the right atrial appendage. In the left atrium, the pectinate muscles are confined to the inner surface of its atrial appendage. They tend to be fewer and smaller than in the

. This is due to the embryological origin of the auricles, which are the true atria. Some sources cite that the pectinate muscles are useful in increasing the power of contraction without increasing heart mass substantially. Pectinate muscles of the atria are different from the trabeculae carneae, which are found on the inner walls of both ventricles. The pectinate muscles originate from the crista terminalis.

Name

The pectinate muscles are so-called because of their resemblance to the teeth of a comb, as in pecten.

References

External links

* * * - "Right atrium, internal structure, anterior view" Cardiac anatomy {{circulatory-stub