Extracardiac and Thoracic Anatomy and Physiology
What you must know
Understand the mediastinal divisions and their contents, the relationships of the great vessels, and the thoracic windows used in echocardiography. The parasternal window looks through the chest wall; the apical window sits at the point of maximal impulse; the subcostal window looks up through the liver; the suprasternal notch gives the aortic arch and descending aorta. Know that the ascending aorta, SVC, and pulmonary artery share the right parasternal region, while the descending aorta lies posterior and leftward.
Thoracic structures
Review the pleural spaces, the pericardium (fibrous and serous layers, oblique and transverse sinuses), and the diaphragm. Understand lung anatomy enough to recognize how aerated lung degrades ultrasound and why subcostal imaging exploits the liver as an acoustic window. Know the IVC/hepatic vein relationship used to estimate right atrial pressure.
Traps
Questions may ask which window best shows the descending aorta (suprasternal) versus the coronary sinus (apical or parasternal). A common trap is confusing the pericardial sinuses with the pleural recesses, or forgetting that the esophagus lies posterior to the left atrium-relevant to TEE orientation. Another trap: assuming the subcostal view is always inferior; in obese or hyperinflated patients it may be the only usable window.
Rule of thumb
Match structure to window: arch and descending aorta → suprasternal; RV inflow and outflow → parasternal; all four chambers and Doppler alignment → apical; IVC and pericardium → subcostal.
Worked example
A question asks where to measure the IVC for right atrial pressure estimation. The subcostal window, just below the cavoatrial junction, with the vessel entering the right atrium, is the answer.