Plica triangularis is present in –
**Core Concept**
Plica triangularis is a fibroareolar fold of pericardium that forms a triangular fold in the pericardial cavity. It is a remnant of the embryonic mesocardium and plays a crucial role in the development of the heart.
**Why the Correct Answer is Right**
The plica triangularis is a normal anatomical structure that is present in the majority of individuals. It is formed by the fusion of the ventral mesocardium and the dorsal mesocardium during embryonic development. The plica triangularis is not a pathological or abnormal structure, but rather a normal variant that can be observed in the pericardial cavity.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the plica triangularis is not a fold of the visceral pericardium, but rather a fold of the parietal pericardium.
**Option B:** This option is incorrect because the plica terminalis is a different anatomical structure that is located at the apex of the heart, not in the pericardial cavity.
**Option C:** This option is incorrect because the plica terminalis is not a remnant of the embryonic mesocardium, but rather a separate anatomical structure.
**Clinical Pearl / High-Yield Fact**
The plica triangularis is a normal anatomical variant that should not be confused with pathological conditions such as pericardial effusion or pericarditis.
**Correct Answer: D. The pericardial cavity.**