Anatomical variations of the median nerve in the carpal tunnel

Abstract

The median nerve was explored in 100 hands and the variations classified by the Lanz system. Only 47.7% of hands showed the standard anatomy described in textbooks. Rare variations were also found. Knowledge of the variable anatomy of the nerve could help to avoid incomplete decompression at operations for carpal tunnel entrapment and injury to the thenar branch of the nerve. The possibility of double thenar innervation must be considered in preoperative evaluation and in the follow up of median nerve injuries.

Bifid Median Nerve in Trauma Patients: How Rare Is it?

“…We found only seven cases [9,[15][16][17][18][19] of this anomaly after trauma. The hand surgeons must be aware of this anomaly not only in elective cases [20,21] but following trauma as well, where the dissection could become more demanding.…”

Anomalous Median Nerve Position Dorsal to the Flexor Tendons in a Patient With Spastic Hemiplegia and Wrist Pain: Case Report

“…Prior to entering the carpal tunnel in a position volar to the flexor tendons, the median nerve typically resides ulnar to the flexor carpi radialis and radial to the palmaris longus tendon. Although there have been several papers discussing variations in median nerve anatomy in the palm and wrist, including reports of a bifid nerve divided by an anamolous muscle 1 or tendon 2 or a persistent median artery, 3,4 most have focused on variations in recurrent motor branch anatomy [5][6][7][8][9][10][11][12][13] or variations in motor 14 or sensory innervation patterns. 15,24,25 None of these papers have described a median nerve that resided completely dorsal to the flexor tendons within the carpal tunnel.…”

“…Although variations in median nerve anatomy at the wrist have been described, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] they have mostly dealt with recurrent motor branch anomalies. The purpose of this report is to present the case of a hemiplegic patient with chronic wrist pain whose radiologic and operative findings demonstrated an unusual finding of a completely dorsally positioned median nerve within the carpal tunnel.…”

A rare anatomical variant of the thenar branch discovered during open decompression of the median nerve

“…Open operation was subsequently successful, but during the procedure a rare anatomical variant of the thenar branch of the median nerve was discovered [5,6,8].…”

“…A specific danger in endoscopic approach is damaging the thenar branch of the median nerve when anatomical variants are present, particularly the thenar branch variant, where the branch originates from the ulnar side and travels supraligamentously, making it at greater risk of damage [5][6][7].…”