| Summary: | Cranio‐hyolaryngeal relationships are important in regulating respiration, vocalization, deglutition, and regurgitation/reflux. In marine mammals, this area has critical adaptations for these functions underwater. This study explores the in situ configuration of the cranio‐cervical region through CT imaging of 45 specimens from 9 genera of odontocetes (toothed whales, dolphins, porpoises). Analyses of shape of the skull and position of hyoid and larynx show extent of cranial and hyolaryngeal asymmetry is related. Asymmetry is predominately left directed (most pronounced in sperm and beaked whales) and marked by an enlarged left nasal aperture and tilted hyoid. The right side of the hyoid is depressed ventrally, resulting in a larger right piriform sinus. Deviations from typical terrestrial mammal symmetry may be linked to aquatic constraints. Pharyngeal asymmetry may facilitate swallowing larger prey. Lateral displacements of respiratory and digestive tracts assure their complete separation, thus protecting the respiratory tract from fluid entry during feeding. Asymmetry of larynx and pharyngeal spaces allows simultaneous airflow and swallowing, consistent with generating echolocation or communication sounds in tandem with open‐mouthed prey capture.
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