Anatomical Snuffbox
The anatomical snuffbox is a triangular depression on the lateral (radial) aspect of the wrist, visible when the thumb is extended. It overlies the scaphoid bone and radial artery, making it clinically important for assessing scaphoid fractures and radial artery cannulation.
Boundaries
superior
Styloid process of radius
inferior
Base of thumb (first metacarpal)
anterior
Tendons of abductor pollicis longus and extensor pollicis brevis
posterior
Tendon of extensor pollicis longus
lateral
Not applicable (triangular shape)
medial
Not applicable (triangular shape)
Contents
Deep to floor
Within the snuffbox
Nerves
- • Superficial branch of radial nerve (sensory, crosses the roof)
- • Posterior interosseous nerve (deep, motor)
Vessels
- • Radial artery
- • Cephalic vein (originates from dorsal venous network nearby)
- • Princeps pollicis artery (branches from radial)
Muscles
- • Abductor pollicis longus (anterior boundary)
- • Extensor pollicis brevis (anterior boundary)
- • Extensor pollicis longus (posterior boundary)
Clinical Relevance
- •Scaphoid fracture: Tenderness in the anatomical snuffbox after a fall on outstretched hand (FOOSH) strongly suggests scaphoid fracture even if X-ray is negative
- •Radial artery cannulation: The artery is superficial here, used for arterial blood gas sampling and arterial line placement
- •De Quervain's tenosynovitis: Inflammation of APL and EPB tendons at the 1st dorsal compartment, causes pain over the snuffbox
- •Superficial radial nerve injury: Can cause numbness over the dorsal thumb and hand
Study Tips
- ✓Called "snuffbox" because people historically placed snuff (tobacco) here to inhale
- ✓Scaphoid is the most commonly fractured carpal bone
- ✓Radial artery enters the palm through the snuffbox (between 1st and 2nd metacarpal heads)
- ✓De Quervain's is tested with Finkelstein's test (ulnar deviation with thumb in fist)
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Common questions about this region
The scaphoid lies directly beneath the floor of the anatomical snuffbox. Point tenderness here after a FOOSH injury has high sensitivity for scaphoid fracture. Because initial X-rays may be negative, clinical suspicion warrants immobilization and repeat imaging or MRI.
The radial artery is superficial at the snuffbox and wrist, easily compressed against bone, and has good collateral circulation through the ulnar artery (tested with Allen's test). This makes it the preferred site for arterial blood gas sampling and arterial line placement.