What structures form the posterior border of the anatomical snuffbox?

The posterior border of the anatomical snuffbox is formed by the tendon of the extensor pollicis longus (EPL). This muscle originates from the posterior aspect of the ulna and the interosseous membrane, and its tendon runs across the back of the wrist, passing along the radial side and culminating in the base of the thumb. When viewed from a dorsal perspective, the EPL tendon can be easily identified as it is situated on the ulnar side of the snuffbox.

The anatomical snuffbox itself is defined by the borders formed by specific tendons and structures that are relevant in the anatomy of the wrist and the thumb. The extensor pollicis brevis (EPB) and abductor pollicis longus tendons make up the anterior border, while the radial artery runs centrally within the snuffbox. The trapezium bone functions as part of the floor of the snuffbox, but it does not form the posterior border as the EPL does.

Understanding the structure and location of the anatomical snuffbox is crucial in clinical practice, particularly in assessing and managing wrist injuries or conditions, such as scaphoid fractures, which may occur in this region due to its anatomical relevance.