The Berrettini Anastomosis' Morphology and "Probable Zone": A Cadaveric Study

Introduction Neural anastomoses between the median nerve (MN) and ulnar nerve (UN), including the Berrettini anastomosis (BA), influence the sensory innervation of the hand. Although typically asymptomatic, the BA's anatomical variability can have clinical implications, particularly during surgical procedures. This study aimed to investigate the prevalence, anatomical variations, and probable location of the BA in cadaveric hands. Methods A total of 104 fresh Caucasian cadaveric hands (52 donors: 26 males, 26 females) were dissected at the Tilman J. Fertitta Family College of Medicine and Baylor College of Medicine, Houston, TX. The dissections focused on the BA's origin, insertion, and branching patterns. Measurements were taken using vertical and horizontal reference points to map its "probable zone." Data were collected by multiple researchers to ensure accuracy, and discrepancies were resolved by averaging measurements. Prevalence and variations were categorized into five distinct types, with detailed illustrations provided. Results The BA was identified in 80% (83/104) of hands. Type I, with a single connection from the UN to the MN, was the most common (38%). Other patterns included bifurcating (type II), dual origin (type III), reverse (type IV), and complex fibrous networks (type V). The average BA length was 22.03 ± 7.68 mm, with its "probable zone" spanning 26.11-44.21% of hand width and 36.63-50.21% of hand length. Conclusion The BA is a common neural connection with significant anatomical variability. Identifying its "probable zone" provides valuable guidance for surgical procedures, minimizing the risk of sensory deficits in the hand. Further studies are recommended to expand upon these findings.