Anatomical features of connective tissue fixations of nerves: a dissection study of the ulnar and median nerves based on a single case report

BACKGROUND: Peripheral nerves have a distinctive fixation system to surrounding tissues, including connective tissue bridges, fascial sheaths, and bone-fibrous canals. These structures simultaneously ensure mobility of the nerve structures within a certain range and stability of their position, preventing excessive displacement during limb movements. Differences in nerve fixation methods may explain their varying susceptibility to compressive and damaging effects.

AIM: To identify the morphological features of peripheral nerve fixation, including connective tissue structures and their topographic relationships.

METHODS: An anatomical study of peripheral nerve fixation in the free upper limb was conducted. The objects of the study were the ulnar and median nerves. The work was performed on fixed cadaveric material from November 2024 to May 2025. All dissection stages were documented using macrophotographs followed by processing in the graphic editor Figma Design (Figma Inc., USA); anatomical structures were labeled according to the second edition of the International Anatomical Terminology, "Terminologia Anatomica" (TA2).

RESULTS: In the median nerve, fibrous tissue derivatives in the form of bridges were identified near the elbow joint, attaching to the superficial fascia of the arm and forearm. The ulnar nerve in the examined area passed through a longer, dense fibrous canal formed by a thickening of its own fascia. These data expand current understanding of peripheral nerve fixation.

CONCLUSION: The differences in morphogeometric characteristics of the connective tissue formations in the identified attachment variations, albeit observed in a single specimen, indicate that their structure provides biomechanical stabilization of nerve trunks. Macro- and microscopic studies of peripheral nerve fixations in mobile regions of the limbs will allow detailed characterization of changes in the lumen of the canals, their configuration and geometry, and will determine the range of individual variability in the displacement of connective tissue structures (e.g., bridges) during upper limb movement. The results of such studies may provide a morphological basis for a deeper understanding of the pathogenesis and development of effective treatments for nerve compression syndromes in neurology and neurosurgery. The present study is an initial stage of a comprehensive study of the morphobiomechanical principles of the nerve fixation apparatus in mobile regions of the limbs. It continues a line of research established at the Department of Histology of the First Moscow Medical Institute by its head, M.A. Baron, and outlined in his work "Biomechanics at the Microscopic Scale" in 1939.