**Question:** The lateral boundary of the anatomical snuff box is formed by which structure(s)?

**Core Concept:** The anatomical snuff box is a bony prominence located on the lateral aspect of the wrist, formed by the fusion of the radial styloid process and the stylohyoid ligament. It is clinically significant due to its proximity to important structures like the radial artery and the ulnar nerve.

**Correct Answer:** The correct answer is **D**. The lateral boundary of the anatomical snuff box is formed by the fusion of the radial styloid process and the stylohyoid ligament.

**Why the Correct Answer is Right:** The anatomical snuff box is a crucial landmark for identifying the radial artery and the ulnar nerve, both of which pass nearby. The styloid process is a bony projection of the radius, and the stylohyoid ligament is a fibrous band connecting the styloid process to the hyoid bone. Their fusion forms the lateral boundary of the snuff box, contributing to its clinical relevance.

**Why Each Wrong Option is Incorrect:**

A. The ulnar styloid process (Option A) is the styloid process of the ulna, not involved in forming the snuff box.
B. The ulnar nerve (Option B) is situated within the snuff box, not as a boundary component.
C. The stylohyoid ligament (Option C) is a fibrous band connecting the styloid process to the hyoid bone, but it is not responsible for the lateral boundary of the snuff box.
D. The radial styloid process and stylohyoid ligament (Option D) are the correct components forming the lateral boundary of the snuff box, as explained above.

**Clinical Pearl:** Understanding the anatomy of the anatomical snuff box allows for proper identification and palpation of the radial and ulnar nerves, as well as the radial artery. This knowledge is essential for clinical examination and diagnosis of disorders affecting these structures.