What Is the Hyoid Bone and Its Function?

Skeleton highlighting the hyoid bone and larynx.
Skeleton highlighting the hyoid bone and larynx. maya2008

The little talked about hyoid bone is a unique part of the human skeleton for a number of reasons.

First, it's mobile. This means that other than its attachment site to the thyroid cartilage, which is part of the larynx and discussed below, it floats. You can even move your hyoid from side to side — for safety's sake, very gently —  by lightly touching either end, and then alternating an ever so slight pushing action that moves the bone.

(This is called palpating the hyoid bone.)

Second, from breathing to eating, the hyoid bone plays roles in a number of key functions that keep you alive.

Location of the Hyoid Bone

The hyoid is situated at the front, or anterior, part of the neck between the jaw bone and the thyroid cartilage, and is firmly secured to the thyroid cartilage by ligaments. It resides at the level of the 3rd cervical vertebra, attaching, by means of tendons to muscles of tongue, the floor of the mouth and the anterior neck.

Although it is small, the hyoid bone is only rarely fractured. This is due to its location which generally protects the bone from all but direct trauma.

The hyoid bone is located above the Adam's apple and below the tonsils and the epiglottis. While not technically a part of the larnyx, at the top, the two structures are very close. The hyoid provides an attachment site for muscles that control movements of the larynx.

  

The larynx is the area above your windpipe, aka trachea, that helps protect you from choking on foreign objects. Perhaps the most well known example of this is when food "goes down the wrong pipe."   The larynx does its primary job of protecting you from choking by quickly closing off the opening to the trachea when a foreign object tries to enter.

Remember, the windpipe is build for air, not things.

Another thing the larynx does — and something we're all pretty familiar with — is to produce sound; singers and speakers know the larynx as the voice box.

Another thing the larnyx is responsible for is coughing, which is part of the choking protection mechanism function mentioned above.

The larnyx has a few other purposes, as well, including playing a role in ventilation and functioning as a sensory organ.

Hyoid Bone Function

The hyoid bone provides a place of attachment for several anterior (front) neck muscles. The muscles that attach onto the hyoid bone include, but are not limited to, the sternohyoid, mylohyoid, omohyoid, digastric muscles. These and other anterior neck muscles play a role in swallowing and may be affected in cases of neck injuries or misalignment.

A second function of the hyoid bone is to provide a foundation or base from which the tongue can move. 

And, finally, the hyoid bone is involved in respiration. This is because it plays a role in keeping the airway open. But not only is an open airway important for breathing, it is especially relevant to sleep and sleeping disorders. An example is sleep apnea.

The Hyoid's Role in Some Medical Conditions

Any way you slice it, the hyoid bone has numerous direct and indirect to connections to muscles and bones in the neck, head and jaw.

And experts tend to agree that the skull, neck and jaw interact to produce a number of different functionalities, not the least of which is the control of posture in the neck.

The skull, neck and jaw, then, is often referred to as the cranio-cervical mandibular system. Let's unpack this term: Cranio refers to the skull, cervical refers to the area of the spine that comprises the neck and mandibular refers to your jaw. The system includes not only bones, but muscles and ligaments, as well 

But in 2017, A European researcher pointed out that the cranio-cervical mandibular system does not really have anatomical connections to the back of the head.

Because of this, he says, the cranio-cervical part of the term is an inaccurate way to describe the system, especially since many of the functions it is supposed to contribute to reflect, in part, that posterior skull area.

Based on his observations, the researcher proposed a re-interpretation, to be made up of the mandible, or jaw, bone, the tongue and the hyoid bone. He claims this renaming will help explain certain medical conditions that affect swallowing, such as Eagle syndrome. Eagle syndrome symptoms include neck pain, problems swallowing, earaches, and more.

Source:

Messina, G. The Tongue, Mandible, Hyoid System. Eur J Transl Myol. Feb 2017.

Moore, K., Dalley, A. Clinically Oriented Anatomy. Fifth. Edition. Lippincott, Williams & Wilkins. 2006. Baltimore.

Porr, J., D.C., et. al. Traumatic hyoid bone fracture - a case report and review of the literature.  J Can Chiropr Assoc. Dec 2012. Accessed Aug 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501913/

 

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