Judney Cley Cavalcante, Bento João da Graça Azevedo Abreu, Wigínio Gabriel de Lira-Bandeira, Mauro Bezerra Montello, Nicol Zielinska, Łukasz Olewnik. Anat Cell Biol -0001;0:. https://doi.org/10.5115/acb.25.118

The omohyoid muscle is the most variable component of the infrahyoid musculature and frequently displays atypical origins, insertions, and fusions with neighboring muscles. During routine dissection of the neck in a middle-aged female cadaver fixed in 10% formalin, we identified an unrecorded unilateral variant in which the omohyoid was absent and replaced by a sternocleidohyoid muscle. This muscle arose from distinct sternal and clavicular heads that joined to form a common belly, continued into a true intermediate tendon firmly attached to the wall of the internal jugular vein, and ascended to insert into the hyoid bone while remaining completely separate from a normally developed sternohyoid muscle. Within the recently proposed classification of the omohyoid, this configuration is consistent with a Type IIIA variant, combining an additional sternal belly with an anomalous clavicular origin. Awareness of such omohyoid-replacing variants is essential to avoid misinterpretation of imaging, to prevent inadvertent injury during neck surgery and reconstructive procedures, and to maintain accurate identification of muscular and venous landmarks during ultrasound-guided or open cervical interventions.

Background: Extranumerary nasal conchae, including the supreme nasal concha (SupNC) and Zuckerkandl’s concha (ZC), are uncommon variants relevant to endoscopic sinus and skull base surgery, yet their prevalence and morphometry remain poorly defined. No cadaveric study has simultaneously evaluated prevalence, detailed morphometry, and a data-driven SupNC classification using principal component analysis (PCA). This study determined SupNC prevalence in cadavers and proposed a clinically oriented classification integrating morphological and quantitative parameters. Material and methods: A cross-sectional cadaveric study analyzed 59 hemisections with preserved nasal conchae. Conchae were counted, and SupNCs classified according to Orhan and a new system. Morphometry was obtained using digital calipers and ImageJ. Results: Of 59 hemisections, 37 (63%) had three conchae, 21 (35%) four, and 1 (2%) five. SupNC was present in 22/59 (37.3%) and ZC in 1/59 (1.7%), associated with SupNC. Significant differences were found between hemisections with and without extranumerary conchae in middle concha area (3.68 ± 1.07 vs. 4.45 ± 1.20 mm ² ), superior concha area (1.26 ± 0.40 vs. 0.94 ± 0.36 mm ² ), length (26.13 ± 4.19 vs. 21.93 ± 3.94 mm), and height (0.72 ± 0.24 vs. 0.45 ± 0.13 mm). Concha number strongly correlated negatively with nasal cavity height (r = –0.83). PCA identified two clusters: Straight (Type I) and Triangular (Type II) SupNCs. Conclusion: SupNC was relatively common, whereas ZC was rare. The proposed morphology- and morphometry-based classification may improve preoperative CT evaluation and intraoperative orientation.