The proximal pole of the scaphoid is prone to avascular necrosis after a waist fracture because its blood supply:

• A Enters the tubercle and runs proximally
• B Enters the distal pole and runs retrograde proximally ✓
• C Comes from the deep branch of the ulnar artery
• D Is derived equally from palmar and dorsal carpal arches at both poles

Explanation

The scaphoid is supplied mainly by branches of the radial artery entering the distal half dorsally. These vessels course retrograde to supply the proximal pole, so a waist or proximal pole fracture can sever the entire inflow to the proximal fragment, causing avascular necrosis and non-union. The tubercle supplies only the distal portion, so option A describes the opposite of the vulnerable anatomy.

Reference: Rockwood and Green's Fractures in Adults, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.