Transecting the omohyoid muscle, but what is known of its function? A scoping review.

The omohyoid muscle (OM) is traditionally regarded as a minor infrahyoid depressor of the hyoid bone and is routinely transected during neck surgery. However, its functional significance remains poorly defined. The course of the OM may contribute to more functions than solely hyoid depression. This scoping review aimed to critically evaluate the existing evidence concerning the anatomy, function, anatomical variations, evolutionary origin, and hemodynamic relevance of the OM. A PRISMA-ScR–guided search of PubMed, MEDLINE, and EMBASE was conducted up to May 2025 using the term “omohyoid.” Studies examining anatomy, muscle activity, anatomical variations, clinical manifestations, evolutionary development, and relationships with the internal jugular vein were included. Forty-one studies met inclusion criteria. Fourteen addressed functional aspects, whereas twenty-three focused on anatomical anomalies. Functional investigations were limited and largely indirect. Five studies investigated the evolution of the OM. Electromyographic and ultrasonographic studies suggest that the superior belly contributes to hyoid stabilization, while the inferior belly is activated during neck flexion and increased inspiratory effort, without systematically evaluated functional consequences, even when this belly is transected, missing, or existed as an anomaly. Three case reports described pathological compression of the internal jugular vein by the OM. Overall, evidence regarding its role in cervical fascial tension and venous configuration remains limited. A discrepancy exists between routine surgical transection of the OM and the limited functional evidence supporting its presumed insignificance. The potential role of the inferior belly in modulating deep cervical fascia and protecting IJV patency warrants further investigation. • The omohyoid muscle is frequently transected without consideration of its function. • Its inferior belly may become active during increased inspiratory effort. • It may prevent collapse of the internal jugular vein. • It likely evolved from the sternohyoid during the transition to terrestrial life. • Despite its anatomical presence, its function remains poorly understood. • Anatomical variations in living persons could provide insight into its function.