The anatomy of the cutaneous branches of the cervical plexus and its clinical significance - lesser occipital nerve. A systematic review with meta-analysis.

Background: This review aims to provide a current, comprehensive, and evidence-based overview of the anatomy of the lesser occipital nerve.

Materials and methods: Major online databases (PubMed, Scopus, Embase, ScienceDirect, Web of Science) were searched to identify all studies reporting data on the anatomy of cutaneous branches of the cervical plexus. This review includes original studies containing morphometric and branching pattern data concerning LON. The risk of bias was assessed using the Anatomical Quality Assurance (AQUA) Tool. The authors strictly adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines in this study. This review was registered in the PROSPERO database, ID CRD420251005988.

Results: A total of 13 articles (526 nerves) met all inclusion criteria. LON emerges at the posterior border of the sternocleidomastoid muscle (SCM). It courses superiorly on the occipital area. It can be located using the distance from the y-axis (a line going through the spinal processes of the cervical vertebrae or external occipital protuberance) and the x-axis (a line perpendicular to the y-axis). Several compression sites for LON have been identified and highlighted in the study.

Discussion and conclusions: This is the most comprehensive review of the anatomy of the lesser occipital nerve to date. Because the included studies were of variable quality and had inconsistent methodology, further research is necessary. This study identified standardised landmarks for describing LON anatomy: EOP, MP, SCM border, external auditory canal and the superior nuchal line. Significant progress has been made in identifying the most optimal surgical approaches to regions concerning LON anatomy.