Distal course and variability of the spinal accessory nerve: a cadaveric study with surgical implications

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dc.check.date2027-09-11
dc.contributor.authorStasiewicz, Martyna
dc.contributor.authorO’Flynn, Carrie
dc.contributor.authorHand, Collette K.
dc.contributor.authorToulouse, André
dc.date.accessioned2026-10-21T15:49:01Z
dc.date.available2026-10-21T15:49:01Z
dc.date.issued2026-09-11
dc.description.abstractPurpose: The spinal accessory nerve (SAN) is most vulnerable to injury along its distal extracranial course in the posterior cervical triangle. While proximal anatomy is well described, distal branching patterns and cervical plexus contributions to trapezius innervation remain poorly defined. This study aimed to characterise distal extracranial SAN branching and cervical plexus contributions and to assess whether proximal configurations predict distal trapezial innervation. Methods: Ten sides from five adult cadavers were dissected from the emergence of the SAN at the posterior border of the sternocleidomastoid muscle (SCM) to its intramuscular termination in the trapezius. Emergence level, SCM branching pattern (Shiozaki classification), cervical plexus communications, loop formations, and distal branching were recorded. Linear morphometric measurements were obtained where feasible. Results: The SAN entered the posterior cervical triangle at variable levels (4.5–8.5 cm from the mastoid). Only Shiozaki Type A and B SCM patterns were identified. Cervical plexus contributions were present in all specimens. An independent cervical branch to the superior trapezius occurred in 6/10 sides, and SAN-cervical loop formation in 2/10 sides. Distal intramuscular branching ranged from two to five terminal branches, with no clear relationship to proximal configuration or measurements. Conclusion: Distal SAN anatomy is highly variable and cannot be predicted from proximal patterns or surface landmarks alone, underscoring the need for meticulous identification of both the SAN and cervical contributions during posterior cervical triangle and trapezius-based surgery.en
dc.description.versionAccepted Version
dc.format.extent10
dc.format.mimetypeapplication/pdfen
dc.identifier.articleid227
dc.identifier.authororcidStasiewicz, Martyna
dc.identifier.authororcidO’Flynn, Carrie
dc.identifier.authororcidHand, Collette K.§0000-0003-2348-5058
dc.identifier.authororcidToulouse, André§0000-0002-4045-8265
dc.identifier.citationStasiewicz, M, O’Flynn, C, Hand, C K & Toulouse, A 2026, 'Distal course and variability of the spinal accessory nerve: a cadaveric study with surgical implications', Surgical and Radiologic Anatomy, vol. 48, no. 1, 227, pp. 1-10. https://doi.org/10.1007/s00276-026-03994-9
dc.identifier.doi10.1007/s00276-026-03994-9
dc.identifier.endpage10
dc.identifier.issn0930-1038
dc.identifier.issued1
dc.identifier.journaltitleSurgical and Radiologic Anatomy
dc.identifier.startpage1
dc.identifier.urihttps://hdl.handle.net/10468/19491
dc.identifier.volume48
dc.language.isoen
dc.publisherSpringer-Verlag Italia s.r.l.
dc.relation.urihttps://www.scopus.com/pages/publications/105050205548
dc.rights© 2026, the Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature. This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://link.springer.com/article/10.1007/s00276-026-03994-9#Abs1
dc.rights.accessrightsembargoed access
dc.statusPeer reviewed
dc.subjectAnatomical variation
dc.subjectCervical plexus contribution
dc.subjectPosterior cervical triangle
dc.subjectSpinal accessory nerve
dc.subjectTrapezius muscle
dc.subject[Medicine]
dc.titleDistal course and variability of the spinal accessory nerve: a cadaveric study with surgical implicationsen
dc.typeArticle (peer-reviewed)
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