With the exception of the cervical vertebrae, the hyoid bone is the only bone located in the anterior neck. Unlike other bony structures, the hyoid bone does not directly articulate with other bones. Instead, it is connected to neighbouring bones by muscular and ligamentous attachments.
Muscles that insert on the upper surface of the bone are known as suprahyoid muscles, while those attached to the lower surface are infrahyoid muscles. This article will explore the embryology, anatomy and muscular attachments of this structure.
The hyoid bone is a U-shaped bone that is held in place by the strap muscles of the anterior triangle of the neck. The bone has a central body (forming the center of the “U”) with two smaller protruding structures on the superior surface (lesser horns) and two larger bony protrusions from the body (greater horns).
The body is quadrilateral, laterally stretched and irregular in shape. It forms the convexity of its classical U-shape, with its outer (anterior) border forming the outer convexity and the inner (posterior) border forming the concavity. There is a vertical median ridge located in the midline of the body that rarely projects to the lower surface. The body is situated at an oblique angle with the anterior end pointing superiorly and the posterior end pointing inferiorly. Immediately posterior to the body of the hyoid bone is a bursa, thyrohyoid membrane and areolar tissue that separates the hyoid bone from the epiglottis.
The greater cornua (horns) extend from the lateral extremity of the body in a posterolateral direction. They are wider proximally and become increasingly narrow until they terminate in tubercles. They are also flattened horizontally.
At the junction of the body and each greater cornu is a conical protruding bone known as the lesser cornua (horns). Fibrous tissue connects the lesser cornua to the body of the hyoid bone. There are also instances where each lesser cornu articulates with the ipsilateral greater cornu by way of a synovial joint that ossifies in later decades of life.
Quiz yourself to reinforce what you have learned about the hyoid bone.
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