**Question:** Roof of anatomical snuff box is formed by:

A. Pronator Teres muscle
B. Pisotriquetral joint
C. Radial collateral ligament
D. Pisiform bone

**Core Concept:**
The anatomical snuff box is a bony prominence located on the lateral aspect of the wrist, between the styloid process of radius and the pisiform bone. It is a common site for tenderness in various wrist conditions.

**Why the Correct Answer is Right:**
The roof of the anatomical snuff box is formed by the D-shaped pisiform bone. The pisiform bone is a small bone located in the wrist, connecting the triquetral bone (one of the carpal bones) to the flexor carpi ulnaris tendon. Its shape allows it to act as a roof for the snuff box, providing a bony prominence for palpation, which can indicate various wrist pathologies.

**Why Each Wrong Option is Incorrect:**
A. Pronator Teres muscle is a muscle located in the forearm that flexes the wrist and supinates the forearm. It does not form the roof of the snuff box.
B. Pisotriquetral joint is a synovial joint between the pisiform bone and triquetral bone, not a structure forming the roof of the snuff box.
C. Radial collateral ligament is a complex of ligaments connecting the radius and ulna to the carpal bones, not a structure forming the roof of the snuff box.

**Clinical Pearl:**
Palpating the roof of the anatomical snuff box can be helpful in diagnosing various wrist conditions, such as tendinitis, ganglion cysts, or fractures involving the pisiform bone. Familiarity with the anatomy of the snuff box can aid in physical examination skills and accurate diagnosis of wrist pathologies.