An Interdisciplinary Review of the Zygomaticus Muscles: Anatomical Variability, Imaging Modalities, and Clinical Implications.

The zygomatic major and zygomatic minor muscles play a central role in facial expression, particularly in generating the smile, one of the most essential forms of human nonverbal communication. While their function is widely recognized, the anatomical variability in these muscles remains underexplored in both clinical and surgical settings. This review provides a comprehensive, interdisciplinary analysis of the zygomaticus musculature, integrating classical anatomical insights with recent advances in imaging, developmental biology, and artificial intelligence-based analysis. By examining data from cadaveric dissection, MRI, ultrasonography, and 3D photogrammetry, we identify key morphological differences with potential clinical relevance. A novel five-type morphological classification is proposed, based on differences in the number of muscle bellies (i.e., belly number), accessory structures, insertion patterns, and population-based variation. This classification aims to offer a more functionally relevant and clinically applicable framework for use in facial surgery, aesthetic procedures, and forensic reconstruction. By moving beyond the simplistic binary categorizations that have historically defined zygomaticus morphology, this review highlights the need for a personalized approach to facial anatomy, tailored to individual morphological variation. The proposed framework may assist in refining surgical planning, improving outcomes in facial reanimation, and enhancing diagnostic accuracy in both radiological assessment and preoperative planning. By moving beyond traditional binary categorizations, this review highlights the need for a personalized approach to facial anatomy, tailored to individual morphological variations. The proposed framework may assist in refining surgical planning, improving outcomes in facial reanimation, and advancing diagnostic precision in facial imaging. A total of 75 peer-reviewed articles were selected based on a targeted search in PubMed, Scopus, and Web of Science (1995-2024).