**Core Concept**
The posterolateral anconeus triangle is a superficial anatomical landmark on the elbow region, bounded by specific muscles and ligaments. It is a clinically relevant area for surgeons and medical professionals to understand the anatomy of the elbow.

**Why the Correct Answer is Right**
The posterolateral anconeus triangle is formed by the anconeus muscle, the lateral epicondyle of the humerus, and the olecranon process of the ulna. The anconeus muscle is a small, triangular muscle that lies posteriorly to the elbow joint and plays a role in extension of the elbow. The lateral epicondyle of the humerus and the olecranon process of the ulna serve as the boundaries of the triangle. Understanding the anatomy of this region is crucial for surgeons performing elbow surgeries.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the anconeus muscle is indeed a part of the posterolateral anconeus triangle.
**Option B:** This option is incorrect as the lateral epicondyle of the humerus is a boundary of the posterolateral anconeus triangle.
**Option C:** This option is incorrect as the olecranon process of the ulna is a boundary of the posterolateral anconeus triangle.

**Clinical Pearl / High-Yield Fact**
It is essential for surgeons to have a thorough understanding of the anatomy of the posterolateral anconeus triangle to avoid injuries to the anconeus muscle and surrounding structures during elbow surgeries.

**Correct Answer: D.**