Cadaveric Study Reveals Anatomical Variations of the Recurrent Thenar Branch of the Median Nerve in the Carpal Tunnel.

Background Carpal tunnel syndrome (CTS) is one of the most prevalent types of entrapment mononeuropathies, necessitating surgical treatment. The median nerve and its branches within the carpal tunnel have anatomical variances that may have clinical implications due to the possibility of iatrogenic injury while undergoing decompression treatments. Methods A total of 40 upper limb specimens (17 right and 23 left) from the Department of Anatomy were used in the dissection investigation. The recurrent thenar branch (RTB) was discovered and identified based on Lanz's classification system. Four characteristics were measured using calipers: flexor retinaculum (FR) width, distances between the superficial palmar arch (SPA) by measuring from the distal border of the FR and the RTB origin, the distance between the proximal border of the FR and the palmar cutaneous branch (PCB) of the median nerve, and the distance between the distal border of the FR and the origin of the RTB of the median nerve. Statistical tests were used to compare the left and right sides, with chi-square tests (χ) analyzing Lanz's classification distribution. Results Of the 40 specimens examined, in 42.5% (n=17), RTB of the median nerve had a subligamentous course (Type 1A), 32.5% (n=13) had an extraligamentous course (Type 0), and 20% (n=8) had a transligamentous course (Type 1B). One (2.5%) specimen had an ulnar variation (Type 1C), while another had an accessory branch (Type 4A). The anatomical relationships of the RTB and accompanying tissues are consistent throughout both sides of the body in the cases examined (p>0.05). Conclusions This study demonstrated significant anatomical variations of the median nerve in the carpal tunnel with a focus on the RTB. The high incidence of transligamentous RTB emphasizes the need for meticulous surgical planning during carpal tunnel release procedures to avoid nerve injury.