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Pectinate muscles make up the part of the wall in front of this, the right atrial appendage. [citation needed] In the left atrium, the pectinate muscles are confined to the inner surface of its atrial appendage. [1] They tend to be fewer and smaller than in the right atrium.
On the external aspect of the right atrium, corresponding to the crista terminalis, is a groove - the terminal sulcus. [citation needed] The crista terminalis provides the origin for the pectinate muscles. [citation needed]
The sinus venarum (also known as the sinus of the vena cava, or sinus venarum cavarum [1]) is the portion of the right atrium in the adult human heart [2] where the inner surface [3] of the right atrium is smooth, [2] [3] whereas the rest of the inner surface is rough [3] (trabeculated [2]) due to the presence of pectinate muscles. [4]
The right atrial appendage is a pouch-like extension of the right atrium and is covered by a trabecula network of pectinate muscles. The interatrial septum separates the right atrium from the left atrium; this is marked by a depression in the right atrium – the fossa ovalis. The atria are depolarised by calcium. [6]
The terminal sulcus is a groove on the outer surface of the right atrium of the heart marking the transition between the sinus venarum cavarum (which has a distinct embryological origin) and the rest of the right atrium (which features pectinate muscles on its inner surface).
Internally, the crista terminalis is a prominent muscle bundle from which the pectinate muscles of the right atrium originate. The terminal crest corresponds to the external sulcus terminalis. [14] [12] The fossa ovalis lies on the interatrial wall and is the remnant of the prenatal atrial communication. [12]
The AV node receives two inputs from the right atrium: posteriorly, via the crista terminalis, and anteriorly, via the interatrial septum. [8] Contraction of heart muscle cells requires depolarization and repolarization of their cell membranes. Movement of ions across cell membranes causes these events.
The trabeculae carneae (columnae carneae or meaty ridges) are rounded or irregular muscular columns which project from the inner surface of the right and left ventricle of the heart. [1] These are different from the pectinate muscles, which are present in the atria of the heart. In development, trabeculae carneae are among the first of the ...