The Anatomical Variations of the Nerve to Obturator Internus, the Levator Ani Nerve, the Nerve to Coccygeus, and Their Clinical Significance: A Scoping Review Protocol
Year: 2026
Type: preprint
Study design: Study Protocol
Abstract: The nerves to the obturator internus (NOI) and levator ani (LAN) are derived from the lumbosacral plexus. NOI also supplies superior gemellus. NOI follows a similar pathway to the pudendal nerve, exiting the greater sciatic foramen inferior to piriformis, passing around the ischial spine and re-entering the pelvis via the lesser sciatic foramen. LAN is closely related to lumbosacral plexus branches to the coccygeus and external anal sphincter. Their territory of distribution to the pelvic floor and organs makes them potential factors in CPP, along with other pelvic organ disorders. While the courses of these nerves have been described, studies have demonstrated anatomical variations in their origins, branching patterns and relationships with surrounding structures, potentially with clinical implications. Objective: Through a systematic search, map the reported anatomy and anatomical variations of the NOI and LAN, including their relationships with associated structures, and examine the potential clinical significance of these variations. We will briefly discuss the nerve to coccygeus and the nerve to external anal sphincter as well. Method: The JBI methodology for scoping reviews will be referenced and PRISMA-ScR will be used to report findings. Eligible sources are primary anatomical studies reporting original observations in humans of any age (including fetal specimens), sex or health status. Case reports and case series are eligible, with no minimum sample size and no date restriction. Sources that do not report original data, such as reviews, textbook chapters, editorials, opinion, commentary and conference abstracts, are excluded but may be cited as background. Only English-language publications are eligible. MEDLINE and Embase (Ovid) will be searched with the assistance of a medical librarian. Records will be screened by two independent reviewers in Covidence, with disagreements resolved by discussion or a third reviewer. References will be managed in Zotero. Expected outcomes: A descriptive mapping of the reported variations in each nerve, with schematic illustrations of the variations. Discussions of reported clinical implications and identification of evidence gaps, including the anticipated asymmetry between the LAN and the NOI literatures.
Language: English
Topic: Peripheral Nerve Disorders
Subfield: Clinical Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7204486331