The hyoid bone is a distinctive, U-shaped structure found in the anterior region of the neck. It holds a unique position in the human body as it is the only bone that does not directly connect or articulate with any other bone. Instead, it remains suspended by a complex network of muscles and ligaments.
Anatomy and Location
The hyoid bone’s U-shape, sometimes described as horseshoe-shaped, comprises a central body and two pairs of projections, known as horns or cornua. The larger extensions are called the greater cornua, while the smaller ones are the lesser cornua. These parts provide attachment points for muscles and ligaments.
This bone is located in the anterior neck, positioned between the lower jaw (mandible) and the thyroid cartilage, often referred to as the “Adam’s apple.” At rest, it typically lies at the level of the third cervical vertebra. Its stability comes from suspension by numerous muscles originating from the tongue, pharynx, larynx, and the floor of the mouth, as well as ligaments connecting it to the skull and thyroid cartilage.
Primary Functions
The hyoid bone plays a role in the process of swallowing, also known as deglutition. It serves as an anchoring point for muscles that elevate the larynx and depress the mandible, facilitating the coordinated movement needed for food and liquid to pass into the esophagus. This upward and forward movement helps open the upper esophageal sphincter.
Beyond swallowing, the hyoid bone contributes to speech and voice production. It provides support for the tongue, enabling the precise movements needed for articulation and modulation of vocal sounds. The bone’s unique suspension allows for the intricate mobility of the tongue and larynx, supporting the wide range of sounds produced during speech. Additionally, its position and muscle attachments contribute to maintaining an open airway.
Clinical Significance
The hyoid bone is important in forensic investigations, particularly in cases of suspected manual strangulation. Fractures of this bone suggest significant compressive force was applied to the neck. Such fractures are more common in older individuals where the bone has fully ossified.
Its position also influences conditions like obstructive sleep apnea (OSA). In individuals with OSA, the hyoid bone is often found in a lower position, which can lead to the tongue shifting backward and reducing the airway space. Surgical procedures, such as hyoid suspension, can reposition and stabilize the bone to improve airway patency. The hyoid bone also serves as a landmark in certain medical procedures, including tracheostomy, and its movement is assessed in the evaluation of swallowing disorders.