Question

Identify the boundaries of the anatomical structure marked in the image.

• A. Extensor pollicis longus
• B. Abductor pollicis longus
• C. Styloid process of the radius
• D. All of the above

Hint:

This triangular hollow on thumb extension is bounded by three named structures, not one.

Answer 1

The Correct Option is D

Step 1: The marked structure is the anatomical snuffbox, a triangular depression on the radial side of the wrist seen on thumb extension.

Step 2: Its boundaries are the medial (ulnar) border formed by the tendon of extensor pollicis longus, the lateral (radial) border formed by the tendons of extensor pollicis brevis and abductor pollicis longus, and the proximal border formed by the styloid process of the radius. The floor is the scaphoid and trapezium.

Step 3: Since extensor pollicis longus, abductor pollicis longus and the radial styloid process are all boundaries, the correct answer is All of the above.

Clinical pearl: tenderness in the snuffbox suggests a scaphoid fracture, and the radial artery crosses its floor.

Ref: BDC, Textbook of Anatomy, Upper Limb.