The bump visible in the front of the neck, often called the Adam’s Apple, is frequently mistaken for the hyoid bone, a structure located nearby. While both are located in the upper throat and move during speech and swallowing, they are fundamentally distinct anatomical structures. One is a cartilaginous shield that protects the voice box, and the other is a unique bone that anchors the tongue.
Defining the Laryngeal Prominence
The structure commonly known as the Adam’s Apple is anatomically termed the laryngeal prominence, a feature of the thyroid cartilage. This cartilage is the largest piece of the larynx, or voice box, and is composed of firm yet flexible hyaline cartilage. The prominence forms where the two plates of the thyroid cartilage meet at an angle in the front of the throat, creating a visible protrusion.
The larynx is the protective housing for the vocal folds, which vibrate to produce sound. The function of this shield-shaped cartilage is to safeguard the vocal cords and other laryngeal structures from external injury. It also regulates voice pitch by providing an anchor point for muscles that adjust the tension of the vocal folds.
The visibility of the laryngeal prominence is an example of sexual dimorphism, becoming more pronounced in males after puberty. This growth is spurred by testosterone, which causes the thyroid cartilage to enlarge and tilt slightly forward. The angle of the cartilage plates is more acute in post-pubescent males (around 90 degrees) compared to females (often around 120 degrees).
Understanding the Hyoid Bone
The hyoid bone is a crescent- or horseshoe-shaped structure situated in the anterior midline of the neck, positioned superior to the thyroid cartilage. It is the only bone in the human body that does not articulate directly with any other bone. Instead, it is suspended in place by a complex arrangement of muscles and ligaments, earning it the nickname “floating bone.”
This unique suspension allows the hyoid to serve as an anchor point for numerous muscles involved in tongue movement and the floor of the mouth. Its U-shape provides a stable base for the tongue, which is essential for manipulating food during chewing and preparing it for swallowing. The hyoid bone is directly involved in deglutition, or swallowing, moving upward and forward to elevate the larynx.
The hyoid’s movement helps close the airway, ensuring food and liquid are directed into the esophagus rather than the windpipe. Due to its connections to the tongue, pharynx, and larynx, the hyoid participates in various functions, including breathing, mastication, and speech.
Structural and Functional Comparison
The laryngeal prominence and the hyoid bone are often confused due to their close proximity in the neck, but they differ significantly in material composition, articulation, and function. The prominence is formed by the thyroid cartilage, a flexible connective tissue, while the hyoid is a rigid bone. The cartilage of the prominence is part of the larger laryngeal framework, whereas the hyoid is an entirely separate, solitary bone.
In terms of connection, the laryngeal prominence is an integral part of the larynx’s cartilaginous skeleton, articulating with other cartilages like the cricoid cartilage. The hyoid is situated superior to the prominence, connected to it only indirectly via the thyrohyoid membrane and various muscles.
Their primary roles are distinct. The prominence’s function is to protect the vocal cords and regulate voice production within the larynx. The hyoid bone’s function is to support the tongue and act as the muscular anchor necessary for the mechanics of swallowing.
Both structures appear to move together because during swallowing, muscles attached to the hyoid bone pull it upward. Since the hyoid is connected to the thyroid cartilage, the entire larynx, including the laryngeal prominence, is simultaneously elevated.