Kaio dos Santos; Alexandre Rodrigues Freire; Camila Carrillo Furlan; Beatriz Carmona Ferreira-Pileggi; Eduardo Daruge Júnior; Felippe Bevilacqua Prado & Ana Cláudia Rossi

The muscles of facial expression function primarily to convey facial emotions, but also play roles as sphincters, dilators, and movers of facial structures. The zygomaticus minor and major muscles are essential for expressing emotions, especially smiling, and exhibit significant anatomical variability. The zygomaticus minor originates from the zygomatic bone and inserts into the skin of the upper lip, playing a crucial role in elevating the upper lip. The zygomaticus major originates near the zygomatic arch and inserts into the orbicularis oris muscle, pulling the angle of the mouth laterally. These muscles show variations in their morphology, including differences in the number of muscle bellies, fiber orientation, and attachment sites. Understanding these variations is fundamental for facial aesthetic surgery, botulinum toxin injections, and forensic craniofacial reconstructions. This study aimed to investigate the anatomical variations of the zygomaticus minor and major muscles in a sample of 70 human cadavers, revealing significant variation in muscle origin, belly structure, and insertion. These findings emphasize the importance of recognizing anatomical differences in clinical practices and educational contexts, particularly in procedures involving the middle third.

KEY WORDS: Facial expression; Muscles; Anatomy; Zygoma.

DOS SANTOS, K.; FREIRE, A. R.; FURLAN, C. C.; FERREIRA-PILEGGI, B. C.; DARUGE JÚNIOR, E.; PRADO, F. B. & ROSSI, A. C. Anatomy and incidence of the variations of zygomaticus minor and zygomaticus major muscles in a Brazilian sample. Int. J. Morphol., 44(2):574-579, 2026.