Cervical anatomical variants: Embryological basis and surgical relevance in neck dissection - a narrative review

Neck dissection (ND) is a pivotal procedure in the management of malignancies of the upper aerodigestive tract, serving both diagnostic and therapeutic purposes. Owing to the complexity and variability of cervical anatomy, precise knowledge of key anatomical structures and their potential variants is essential to minimize perioperative morbidity. This narrative review aims to provide a clear and didactic synthesis of the most clinically relevant anatomical variations encountered during ND, linking them to their embryological origin, to enhance surgical accuracy and safety.

A non-systematic literature review was performed using PubMed, Scopus, and Google Scholar, with search terms including "anatomic anomalies," "embryological development," "internal jugular vein," "transverse cervical artery," "spinal accessory nerve," "superior thyroid artery," "external carotid artery", "hypoglossal nerve", "lingual nerve", "phrenic nerve" and "thoracic duct" Publications from 1868 to 2025-comprising original research, case reports, reviews, anatomical atlases, and embryological studies-were examined. Extracted data were thematically synthesized and supplemented with original intraoperative iconographic material collected during neck dissections.

Numerous anatomical variations were identified among key cervical structures as the internal jugular vein (IJV), carotid arteries, superior thyroid artery (STA), facial artery (FA), hypoglossal nerve (HN), lingual nerve (LN), phrenic nerve (PN), torachic duct (TD) and vessels of the supraclavicular region. The variants included IJV duplication or fenestration, atypical relationships between the spinal accessory nerve (SAN) and the IJV, tortuosity or kinking of the extracranial internal carotid artery (ICA), and alternative origins of the STA and FA from the common or external carotid artery (ECA). These abnormalities were interpreted in light of embryological mechanisms CONCLUSIONS: A detailed understanding of cervical anatomy and its embryological determinants is indispensable for the safe and effective performance of ND. Awareness of these variations enables surgeons to anticipate atypical configurations, reduce iatrogenic risk, and optimize reconstructive strategies.