## Anatomical Snuffbox — Boundaries The anatomical snuffbox is a triangular depression on the dorsal aspect of the hand at the base of the thumb. Understanding its boundaries is clinically important for assessing radial artery patency and identifying fractures of the scaphoid bone. ### Medial Boundary **Key Point:** The medial (ulnar) boundary of the anatomical snuffbox is formed by the **Extensor pollicis longus (EPL)** tendon. ### Complete Boundaries of the Snuffbox | Boundary | Structure | | --- | --- | | **Lateral (radial)** | Extensor pollicis brevis (EPB) and Extensor carpi radialis longus (ECRB) tendons | | **Medial (ulnar)** | Extensor pollicis longus (EPL) tendon | | **Floor** | Scaphoid, trapezium, and first metacarpal base | | **Roof** | Skin and superficial fascia containing superficial radial nerve and cephalic vein | ### Clinical Significance **Clinical Pearl:** The radial artery runs through the floor of the anatomical snuffbox. Palpation of the radial pulse in the snuffbox is part of the Allen's test to assess collateral circulation before radial artery cannulation. **High-Yield:** Scaphoid fractures present with tenderness in the anatomical snuffbox — this is the most common carpal bone fracture and may not be visible on initial X-rays. ### Mnemonic for Snuffbox Tendons **LEAP:** **L**ateral = **E**xtensor pollicis **B**revis + **E**xtensor **C**arpi **R**adialis; **M**edial = **E**xtensor **P**ollicis **L**ongus 
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