[Biology Class Notes] on Hyoid Bone Pdf for EXAM

The hyoid bone is a small U- shaped bone found in the midline of the neck anteriorly at the base of the mandible and posteriorly at the fourth cervical vertebra. The primary function of the bone is to form an attachment structure for the tongue and muscles on the floor of the oral cavity. In size, it is 2.5 cm wide by 1 cm thick with greater and lesser horns. 

Hyoid Bone Function

The hyoid bone is located in the front of the neck, right below the lower jaw. It plays a vital role in carrying the weight of the tongue and in speech and swallowing. At the time of birth, the hyoid bone is made of three unconnected bones, which may or may not form a crescent-shaped structure as we grow. It is the only free-floating bone of our body. The hyoid bone is part of a functional system that gives attachment to the tongue’s muscles, the larynx, the mandible, and other structures in the mouth and throat. So, all of them must grow at the right way and speed; otherwise, it will affect the other systems’ functioning and eventually in speech and swallowing. The essential functions that can be classified of Hyoid bone are-

• It acts as the larynx’s attachment point, covering all the larynx tasks and holding it up.

• It provides a  base from which the tongue can move.

• The hyoid bone is involved in respiration. It plays a role to keep the airway open., which helps keep sleeping disorders at bay.

• It helps in transmitting the force of muscles to open the jaw.

Hyoid Bone Anatomy

Hyoid means a horseshoe-shaped bone that holds its place by the neck’s anterior triangle’s strap muscles. The bone forms a central body with two smaller protruding structures on the superior surface and two more significant bony protrusions from the body. The body is laterally stretched and irregular in shape. It forms a U shape body. In the middle, there is a Vertical median ridge that does not project to the lower surface. The body’s situation is at an oblique angle, with the anterior end facing upwardly and the posterior end facing downwardly. Right behind the hyoid bone is a bursa, a membrane that separates the hyoid bone from the epiglottis.

From the sideways from the body in a posterolateral direction, greater cornua extend. They are wide and become narrow till they terminate in tubercles. They also flatten horizontally. At the intersection of the body and each cornu is a conical protruding bone known as the lesser cornua. Fibrous tissue connects the lesser cornua to the body of the hyoid bone.

Hyoid Bone Attachments

Hyoid bone does not articulate with any other bones and is placed in position by the muscles and ligaments that hold it. It is an attachment to many muscles in the neck.

• Oral Cavity and Pharynx- Middle pharyngeal constrictor, Hyoglossus, and Genioglossus.

• Suprahyoid- Digastric, Stylohyoid,Geniohyoid, and Mylohoid.

• Infrahyoid- Thyrohyoid, Omohyoid, and Sternohyoid.

• Hyoid bone attachments as ligaments to support the position in the neck. 

• The stylohyoid ligament moves from the styloid process of the temporal bone to the smaller horn of the bone. 

• Thyrohyoid Membrane- It starts from the higher line of the thyroid cartilage and attaches to the posterior surface of the bone and the more incredible horns.

• Hyoepiglottic Ligament- joins the hyoid to the anterior of the epiglottis.

What is the Hyoid Apparatus?

Hyoid apparatus is a term used in anatomy for the bones which append the tongue and larynx. It comprises pairs of stylohyoid, thyrohyoid, and ceratohyoid bones, and a single basihyoid bone. The shape is like a trapeze or a bent letter H. Human beings have a single hyoid bone like a hyoid apparatus.