Defining a superficial neurovascular corridor in the upper trapezius using proportional surface mapping and cadaveric correlation.

PURPOSE: Precise surface-to-subsurface anatomical correlation within the upper trapezius remains limited. This study aimed to define a reproducible superficial neurovascular corridor using a proportional surface coordinate framework and to examine its regional correspondence with a clinically localised surface-sensitive site.

METHODS

Twenty participants with a clinically localised focal myofascial sensitivity site underwent standardised palpation-based localisation supported by surface electromyography to assist identification of the upper-middle trapezius interface. Site position was expressed as a proportional coordinate along the C7-acromion reference line. Pressure-pain thresholds and referred-pain responses were recorded. Forty-two embalmed cadaver sides from 27 donors were examined using identical surface landmarks to map the superficial neurovascular emergence zone (NAV). A subset underwent dissection, histology, immunofluorescence and immunohistochemistry using CGRP, PGP9.5 and NF200.

RESULTS

Clinically localised sites demonstrated stable proportional positioning near the upper-middle trapezius interface. Pressure-pain thresholds were lower at the localised site than at adjacent controls. Cadaveric mapping identified a consistently positioned superficial neurovascular corridor within the same region. Mean proportional coordinates were closely aligned, although complete geometric concordance was not observed. Histology demonstrated clustered superficial nerve fascicles adjacent to the deep fascia.

CONCLUSION

A reproducible superficial neurovascular corridor can be defined within the upper trapezius using proportional surface mapping. This structured anatomical framework enables consistent surface-subsurface correlation and may provide a reproducible anatomical reference for future investigations of clinically localised myofascial pain and anatomically guided interventions, without implying specific functional or pathological mechanisms.