Ansa cervicalis or ansa hypoglossi? A systematic review

Financial support: None. Conflicts of interest: No conflicts of interest declared concerning the publication of this article. Submitted: June 24, 2019. Accepted: October 02, 2019. The study was carried out at Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo, SP, Brasil. Abstract Introduction: The ansa cervicalis, commonly called ansa hypoglossi, is a loop of nerves that composes the cervical plexus. The term ansa hypoglossi derives from the anastomosis between this loop and the hypoglossal nerve (cranial nerve XII). In the study of Anatomy, discrepancies between the anatomical terminology and the terms used in medical practice are frequent. However, a discussion becomes necessary when these divergences arise from conceptual errors. Objective: To conduct a literature review on the relationship between the ansa cervicalis (or ansa hypoglossi) and the hypoglossal nerve, discussing this disparity in terminology, and determine which of these terms is the most suitable to identify this important nerve structure. Methods: This is a systematic review of the literature based on studies found through a standardized search performed at the LILACS and MEDLINE/PUBMED databases; classic anatomy textbooks were also consulted. Results: Forty-five of the 3731 articles found in the scientific research databases were selected and six classic anatomy textbooks were included in the study. Controversies involving the ansa cervicalis were analyzed and the results clearly showed that most textbooks describe its relationship with the hypoglossal nerve as a temporal junction, with no exchange of nerve fibers. The ansa cervicalis contains fibers arising from the cervical cord, and not from the hypoglossal nerve. Conclusion: The term ansa cervicalis should be chosen to name this loop of nerves. The term ansa hypoglossi is not structurally correct, and should be abandoned in medical practice, the teaching of anatomy, and in scientific publications.