**Core Concept**
The supraventricular crest is a fibrous anatomical structure in the right atrium that separates the pulmonary orifice (opening of the pulmonary valve) from the atrioventricular (AV) orifice (opening of the tricuspid valve). It forms part of the interatrial septum and helps define the boundary between the right atrium and ventricle.

**Why the Correct Answer is Right**
The supraventricular crest lies precisely between the pulmonary orifice and the atrioventricular orifice in the right atrium. This crest is a ridge of fibrous tissue that marks the transition from the pulmonary inlet to the AV inlet, preventing abnormal communication between the atria and ventricles. It is part of the embryological development of the atrial septum and contributes to the structural integrity of the right atrium.

**Why Each Wrong Option is Incorrect**
Option B: The fossa ovalis is a remnant of the fetal foramen ovale, located near the AV orifice, not adjacent to the supraventricular crest. It lies posterior to the AV orifice and does not form a boundary with the pulmonary orifice.
Option C: The SVC (superior vena cava) enters the right atrium near the superior aspect, far from the supraventricular crest. This option confuses a vessel with a structural landmark.
Option D: The coronary arteries run within the myocardium and do not form a boundary in the atrium. This is a complete misdirection of anatomy.

**Clinical Pearl / High-Yield Fact**
The supraventricular crest is a key landmark in cardiac anatomy, especially in surgical procedures involving the right atrium, such as atrial septal defect repair. Remember: it separates the **pulmonary** from the **atrioventricular** orifices — never mix with the fossa ovalis or SVC.

✓ Correct Answer: A. Pulmonary orifice and atrioventricular orifice