Aatriumi

Aatriumi is a term used in Estonian to refer to two distinct concepts that share a common name in Latin: the atrium of the heart and the atrium of a building. In everyday usage, the word appears in medical and architectural contexts, and its exact meaning is clarified by the surrounding text. The word atrium in Estonian is a loanword from Latin atrium, and forms such as aatriumi (genitive or related forms) appear in inflected phrases.

In anatomy, aatriumi are the two upper chambers of the heart, the right atrium and the left atrium. The right atrium receives deoxygenated blood from the systemic circulation via the superior and inferior vena cavae and the coronary sinus. The left atrium receives oxygenated blood from the pulmonary veins. The atria act as reservoirs and conduits to the ventricles, with relatively thin walls and distinct internal features: the right atrium has pectinate muscles in portions and a smooth posterior wall, while the left atrium is mostly smooth with small pectinate areas in the left atrial appendage. The interatrial septum contains the fossa ovalis, a remnant of fetal circulation. The atria participate in the heart’s conduction system and play a role in conditions such as atrial fibrillation, where the atrial appendage is a common site of thrombus formation.

In architecture, an atrium is a large open interior space, often with a skylight and surrounding upper floors, used as a lobby, reception area, or light well. The concept originated in Roman houses as the atrium, typically featuring an impluvium and an opening in the roof (compluvium). In modern buildings, atria enhance natural light, ventilation, and spatial quality, and may house plants, galleries, or public amenities.