Trajche Jovanovski; Nejc Umek & Erika Cvetko

Facial muscles are known to have a variable anatomy. Such anatomical variations can affect facial expressions. A natural smile is produced by contracting several muscles of facial expression, including the muscles invested in the superficial musculoaponeurotic system. Change in the width of the mouth on smiling is a known iatrogenic complication affecting the risorius muscle when using Botulinum Neurotoxin as a non-invasive treatment for masseteric hypertrophy. Also damage to the risorius muscle, with consequent clinical deficits, is a common surgical complication in facial aesthetic, oncologic and other head and neck procedures such as parotidectomy and rhytidectomy. Hence, a thorough knowledge of muscle anatomy, particularly its potential variations, is critical in reducing the associated operative morbidity. Accordingly, we report an unusual variation of the transversus nuchal muscle fused with the risorius muscle noted in an 83-year-old female body cadaver.

KEY WORDS: Anatomical variation; Transversus nuchal muscle; Risorius muscle; Facial expression; Rhytidectomy.

JOVANOVSKI, T.; UMEK, N. & CVETKO, E. Transversus nuchae muscle fused with risorius muscle: A case report. Int. J. Morphol., 38(5):1208-1211, 2020.