Final answer:
The small pouch-like appendage on each atrium is known as an atrial auricle, resembling the external ear in shape and aiding in the heart's blood management.
Step-by-step explanation:
The atrial auricle, a small pouch-like extension on each atrium of the heart, mimics the shape of the external ear. Positioned on the superior surface, these thin-walled structures serve a crucial role in blood management. Functioning as atrial appendages, they facilitate efficient blood flow by filling with blood and subsequently emptying into the atria, the heart's upper chambers. The term "auricle" aptly describes their ear-like appearance. This anatomical feature enhances the heart's capacity to regulate blood circulation, contributing to the overall efficiency of the cardiovascular system.