Vorhofs

Vorhofs, in anatomical terms, are the atria of the heart — the two upper chambers that receive blood returning to the heart and transfer it to the ventricles. The right atrium collects systemic venous blood via the superior and inferior vena cavae and the coronary sinus, while the left atrium receives oxygenated blood from the four pulmonary veins. The atria are separated from the ventricles by the atrioventricular valves and from each other by the interatrial septum.

Anatomy: The right atrium has a smooth posterior wall and a muscular anterior wall with pectinate muscles, and it contains the right auricle. The left atrium has a smooth posterior wall with pectinate muscles confined to the left atrial appendage, and it receives blood from the pulmonary veins. The left atrial appendage is clinically relevant as a potential site of thrombus formation in atrial fibrillation.

Conduction and function: The atria contribute to the cardiac cycle by receiving venous return and providing an atrial contraction (atrial kick) that helps fill the ventricles. The sinoatrial node, the heart’s natural pacemaker, is located in the right atrium near the superior vena cava, while the atrioventricular node resides in the interatrial septum near the right atrium and delays conduction to the ventricles.

Clinical notes: Enlargement, scarring, or abnormal conduction can affect atrial function. Atrial fibrillation involves irregular atrial activity and increases the risk of thromboembolism, and atrial septal defects are congenital communications between the atria. Diagnostic imaging such as echocardiography, CT, and MRI aids assessment.

Development: Vorhofs originate from the primitive atria during embryogenesis; the foramen ovale in the fetal heart allows right-to-left shunting and typically closes after birth, forming the fossa ovalis in the interatrial septum.