genio- definition
genio- means the chin. The geniohyoid is a narrow paired muscle and is one of the four suprahyoid muscles: the digastric, the mylohyoid, the stylohyoid, and the geniohyoid. The muscle lies above the mylohyoid on the medial side in contact with its opposite partner. Occasionally it is not separated as a paired muscle but is contiguous as a single muscle. It may also be fused with the genioglossus, an extrinsic muscle of the tongue. The root of the tongue is in contact with the geniohyoid and the mylohyoid (Gervasio et al., 2011). Like other jaw-opening muscles, it has an architecture to be designed for velocity and displacement rather than force production (Van Eijden et al., 1997). In addition, it is composed predominantly of fibers expressing myosin heavy chain type IIA (Korfage et al., 2000; Luo et al., 2014). In this review, the anatomic features of the geniohyoid are summarized. Functions and malfunctions of this muscle will be discussed, with a focus on swallowing and respiration. Finally, the clinical implications of dysfunction of this muscle will be covered.