Evaluation of median and obturator nerve fascicular topography using landmark morphometrics: a pilot study

While the macroanatomy of peripheral nerves is well-documented, the microanatomy, particularly fascicular arrangement, remains less understood.

This pilot study investigated the variability in fascicle organization within the median and obturator nerves using landmark-based geometric morphometrics. Median and obturator nerves were harvested from 20 formalin-fixed, preserved human donors, segmented, cross-sectioned, imaged, and analyzed. Each median nerve sample contained 8-9 fascicles, while the obturator nerve had 10. Using Procrustes superimposition and principal component analysis, researchers examined spatial fascicle patterns.

Distinct shape variations were observed. In the median nerve, principal component analysis (PC1) revealed a pattern of fascicles expanding toward the periphery, reducing peripheral non-neural tissue and increasing central non-neural tissue. This "expansion" and "collapse" dynamic highlighted internal variability. The obturator nerve showed localized variation among fascicle numbers 4-9, forming a highly variable cluster on one side, while fascicle numbers 1-3 and 10 remained relatively stable.

The findings of this pilot study suggest consistent yet variable fascicular arrangements within nerve trunks, which may influence measurements of non-fascicular tissue. Such variability has potential implications for clinical procedures like nerve grafting, surgical repair, and electrode implantation, due to its individual variability between donors.

By identifying common fascicle patterns and their spatial dynamics, this study contributes to a deeper understanding of nerve microanatomy and supports improved precision in clinical interventions.