QS Study

Musculi Pectinati is a smooth transverse muscular ridge on the lateral wall of the interior of the right atrium. It is a small muscular ridge on the inner wall of the auricular appendage of the left and the right atria of the heart. They are parallel ridges in the walls of the atria of the heart. It is mainly located in the right atrium.


They arise from the cristae terminalis and run forwards-downwards to the atrioventricular orifice. They are interlaced in the auricle to form a reticular network. Pectinate muscles are located mainly in the right atrium, more in right atrial appendage, sparse in the left atrium. This physical structure gets its name from the fact that the muscular fibers located in it are arranged like the bristles of a comb.

Fig: Musculi Pectinati

Development – It develops from the primitive atrial chamber. Since the variation left atrial blood flow is not that much, the pectinate muscles are not well developed in the left atrium. These muscles may also traverse the wall of the adjacent anterior atrium.

Function – These muscles restrict and regulate the displacement of cusps of cardiac valves beyond the maximum point of distention.

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