54 - Anatomical Variations of the Trajectory of the Recurrent Branch of the Median Nerve

Poster Board Number: 54
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Co-authors:

Jaime Arroyo Avilés - San Juan Bautista School of Medicine; Valeria Pauneto - San Juan Bautista School of Medicine; Max Schreiber - San Juan Bautista School of Medicine; Wilson Veras Tavarez - San Juan Bautista School of Medicine

Abstract Body : Background: The recurrent branch of the median nerve controls motor function of the thenar muscles in the hand, facilitating precision grip and dexterous movements while also providing sensory feedback, crucial for tactile discrimination. In this study Poisel’s classification system was used, which establishes three variations of the recurrent branch of the median nerve: extraligamentous, subligamentous, and transligamentous. The extraligamentous type is where the branch arises distal to the flexor retinaculum and curves back to supply the thenar muscles. This classification is described in the literature as the most common variation. The subligamentous type is where the branch arises within the carpal tunnel deep to the flexor retinaculum. After running deep to this ligament, it curves around its distal border to supply the thenar muscles. The third type, the transligamentous type of the recurrent branch, arises within the carpal tunnel and pierces the flexor retinaculum to supply the thenar muscles directly. Awareness of these variations is vital for both clinical examination and for carpal tunnel release surgery.

Aims: The aim of this study was to document the most common anatomical variations of the recurrent branch of the median nerve in a sample of the Puerto Rican population.

Materials and Methods: An observational study was conducted at the Anatomy Lab of San Juan Bautista School of Medicine. Dissection of the palmar aspect of each of the hands was performed following the procedure described in Clemente’s Anatomy Dissector.

Results: Of the thirty-four hands studied, five hands were discarded due to median nerve damage or absence of the recurrent branch, yielding a total of twenty-nine recurrent branches. Eight branches (27.6%) were classified as extraligamentous, nine branches (31%) as subligamentous, and twelve branches (41.4%) as transligamentous.

Conclusion: Our study found a prevalence of the transligamentous variation. These findings differ from what literature has described as the most common variation of the recurrent branch. Awareness of the anatomical variations in position and trajectory of the recurrent branch of the median nerve at the wrist is essential during the surgical treatment of compression syndrome of carpal tunnel. Familiarity with these variations will prevent injury to the recurrent branch of the median nerve during the surgical decompression of the carpal tunnel in patients affected by this syndrome. Further studies should be performed in order to determine if the Puerto Rican population deviates from what other authors have found in their research or if the results obtained were not truly representative of the population due to a small sample size.