The extensor tendons passing into the thumb forms the triangular depression called “anatomical snuffbox” on the posterolateral side of the wrist and metacarpal I. In this depression, the ground tobacco (snuff) is placed before it is inhaled into the nose. The apex of the anatomical snuffbox is directed into the thumb while the base of the anatomical snuffbox lies at the wrist. The thumb is extended in order to see the impression more apparently:
- The lateral border is formed by the tendons of the abductor pollicis longus and extensor pollicis brevis.
- The medial border is formed by the tendon of the extensor pollicis longus.
- The floor of the impression is formed by the scaphoid and trapezium, and the distal ends of the tendons of the extensor carpi radialis longus and extensor carpi radia- lis brevis.
The radial artery passes obliquely through the anatomical snuffbox, deep to the extensor tendons of the thumb and lies adjacent to the scaphoid and trapezium.
Terminal parts of the superficial branch of the radial nerve pass subcutaneously over the snuffbox as does the origin of the cephalic vein from the dorsal venous arch of the hand.
- The pulsations of radial artery can be felt in the anatomical box.
- The tenderness in the anatomical box indicates fracture of scaphoid bone.
- The cephalic vein at this site is often used for giving intravenous fluids.
- The superficial branches of the radial nerve can be rolled over the tendon of extensor pollicis longus.