Question:medium
Identify the boundaries of the anatomical structure marked in the image.
Identify the boundaries of the anatomical structure marked in the image.
Show Hint
This triangular hollow on thumb extension is bounded by three named structures, not one.
Updated On: Jun 23, 2026
- Extensor pollicis longus
- Abductor pollicis longus
- Styloid process of the radius
- All of the above
Show Solution
The Correct Option is D
Solution and Explanation
Spot diagnosis: a small triangular pit on the radial border of the wrist that deepens when the thumb is extended is the anatomical snuffbox. The question asks which listed item forms a boundary, and the trick is that several do.
Walk the borders. Ulnar (medial) wall is the extensor pollicis longus tendon. Radial (lateral) wall is the paired extensor pollicis brevis and abductor pollicis longus tendons. Proximal base is the styloid process of the radius. So extensor pollicis longus (option a), abductor pollicis longus (option b) and the radial styloid (option c) are each true boundaries, which makes All of the above correct. Remember the floor carries the radial artery and the scaphoid, so snuffbox tenderness flags a scaphoid fracture.
Ref: BDC, Textbook of Anatomy, Upper Limb.
Walk the borders. Ulnar (medial) wall is the extensor pollicis longus tendon. Radial (lateral) wall is the paired extensor pollicis brevis and abductor pollicis longus tendons. Proximal base is the styloid process of the radius. So extensor pollicis longus (option a), abductor pollicis longus (option b) and the radial styloid (option c) are each true boundaries, which makes All of the above correct. Remember the floor carries the radial artery and the scaphoid, so snuffbox tenderness flags a scaphoid fracture.
Ref: BDC, Textbook of Anatomy, Upper Limb.
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