Structure and Location
The body of the hyoid bone (corpus ossis hyoidei) represents the unpaired, broader anterior part of the hyoid bone (os hyoideum). The hyoid bone consists of a body and two pairs of horns: the greater horns (cornu majus) and lesser horns (cornu minus).
The body is situated in the neck region above the larynx, at the level of the third cervical vertebra (C3). When orienting on an anatomical specimen, it is important to note that the anterior border is markedly more convex.
The greater horns (cornu majus) project posteriorly and laterally. The lesser horns (cornu minus) are small, cone-shaped projections at the junction of the body and the greater horns; the stylohyoid ligament (lig. stylohyoideum) typically attaches near them. The body of the hyoid bone does not articulate with any other bones and is suspended by muscles and ligaments.
Muscular Attachments
The following muscles attach to the body of the hyoid bone:
- Mylohyoid muscle (m. mylohyoideus). Originates from the mylohyoid line of the mandible and inserts into the body of the hyoid bone as well as the median raphe (raphe mylohyoidea). This muscle elevates the hyoid bone and the floor of the oral cavity; when the hyoid bone is fixed, it depresses the mandible. It is innervated by the mylohyoid nerve (n. mylohyoideus), a branch of the trigeminal nerve (n. trigeminus), and supplied by the sublingual and submental arteries (aa. sublingualis, submentalis).
- Omohyoid muscle (m. omohyoideus). Originates from the superior border of the scapula (margo superior scapulae) and inserts into the body of the hyoid bone. The muscle possesses two bellies—superior and inferior—connected by an intermediate tendon anchored to the clavicle. Function: tenses the cervical fascia and depresses the hyoid bone. Innervation: ansa cervicalis (C1–C3). Blood supply: inferior thyroid artery and transverse scapular artery (a. thyroidea inferior, a. transversa scapulae).
Topography and Clinical Significance
The body of the hyoid bone serves as the posterior boundary of the fascial space of the submental region.
Other boundaries of this space include:
- Superior boundary: Mylohyoid muscle, covered inferiorly by the deep layer of the deep cervical fascia.
- Lateral boundaries: Anterior bellies of the digastric muscle.
- Inferior boundary: Superficial layer of the cervical fascia.
This fascial space houses the submental lymph nodes.
Odontogenic sources of abscesses and phlegmons in the submental region typically stem from pathological processes in the periapical tissues of the mandibular incisors and canines.