What provides support to the walls of the atria?

The pectinate muscle is a prominent feature found in the walls of the atria, specifically in the right atrium and to some extent in the left atrium. This muscular structure consists of parallel ridges that run along the inner surface of the atrial walls. These muscles help in supporting the structural integrity of the atrial walls, allowing them to handle the volume changes during the cardiac cycle, particularly during atrial contraction.

In addition to providing support, the pectinate muscles also play a role in helping to increase the contractile force of the atria, facilitating efficient blood flow into the ventricles. Their unique architecture allows for optimal expansion and contraction of the atrial walls, which is crucial for maintaining proper cardiac function.

The other options represent important components of the cardiac anatomy but serve different roles. Chordae tendineae are fibrous cords that connect the atrioventricular valves to the papillary muscles, preventing valve prolapse but do not provide direct support to the atrial walls. Atrioventricular valves (tricuspid and mitral) regulate blood flow between the atria and ventricles, while the interatrial septum is the wall that separates the left and right atria; it provides separation