ANATOMICAL VARIATIONS OF MEDIAN NERVE IN CARPAL TUNNEL

INTRODUCTION

Most common entrapment neuropathy Causes Thickening of synovium Frequent anatomic variations

Surgical anatomy of carpal tunnel

Function Attachments Contents Closed compartment Site marking Deep antebrachial fascia and palmar

aponeurosis Anomalous muscle Narrowest and thickest portion

Median nerve

Roots Sensory Motor Course in forearm Palmar cutaneous branch Position in flexion and extension Terminal branches Origin and penetration of thenar

branch

Digital nerves Lumbricals Ulnar to thenar crease

Distal end of carpal tunnel

Palmar arches Marking Communicating branch

between sensory parts of median and ulnar nerve

Deep branch of ulnar nerve

Variations

Recurrent motor branch

Extreme radial to anterior 20% anomalous origin 12.5% multiple motor branches 56% separate tunnel

Group 2 variations

Duplication of motor br + thin sensory branch

Transligamentous to abductor, opponens , extraligamentous to flexor

Accessory sensory br with TCDN arising proximally

Median nerve within carpal tunnel

Variations of TCDN

Martin Gruber anastomosis

Between ulnar and median nerve in forearm

Rarely in distal forearm and palm Variations Subtypes

Marinacci communication Riche Cannieu Berretini