The , commonly known as the atrial appendage or auricle of the heart , is a small, muscular, ear-shaped pouch that projects from each of the heart's two upper chambers (atria). Key Anatomical Features
: These appendages have a rough, trabeculated inner surface due to a network of pectinate muscles , which distinguishes them from the smoother main bodies of the atria. Location : auricula atrii
: They act as "reservoirs" that can expand to increase the capacity of the atria during periods of high cardiac output or when blood flows quickly back to the heart. The , commonly known as the atrial appendage