What is an auricle of the heart?

The auricle of the heart, also known as the atrial auricle or auricular appendage, is a small, ear-shaped structure located on the upper surface of each atrium in the heart. There are two auricles in the human heart, one in the right atrium and one in the left atrium.

The auricles serve as extensions or pouches that increase the overall capacity of the atria, allowing them to hold a larger volume of blood. This increased capacity enables better filling of the ventricles, enhancing the efficiency of the heart's pumping action.

Structurally, the auricles consist of muscular walls that are lined with endocardium, the innermost layer of the heart. The walls contract and relax rhythmically, facilitating the movement of blood into the ventricles during the diastolic phase of the cardiac cycle.

The auricles contain numerous blood vessels, nerve endings, and specialized cells called pacemaker cells that play a role in initiating and coordinating the heartbeat. These cells generate electrical impulses that regulate the heart's contractions, helping to maintain a steady rhythm.

In addition to its functional role, the auricle can also be a site for the formation of blood clots. Due to its relatively stagnant blood flow and complex internal structures, blood can pool, leading to the formation of thrombi. These thrombi can detach and travel through the bloodstream, potentially causing a blockage in smaller blood vessels known as embolism.

Overall, the auricles contribute to the efficient functioning of the heart by increasing the atrial volume and aiding in the coordination of electrical signals for proper cardiac rhythm.