The thyrohyoid muscle is a small, strap-like muscle located in the neck. It originates from the thyroid cartilage and inserts onto the greater cornu of the hyoid bone. It is innervated by the cranial nerve XII (the hypoglossal nerve) and is supplied by a branch of the ventral rami of the cervical plexus, spinal nerve C1, which travels with the hypoglossal nerve.
The primary function of the thyrohyoid muscle is to move the larynx. When it contracts, it pulls the hyoid bone downward and the larynx upward, which helps to open the airway and allows for easier breathing. In addition to its role in respiratory function, the thyrohyoid muscle also plays a role in the production of speech. By controlling the position and shape of the larynx, it helps to tense the vocal cords and produce higher-pitched sounds.
Structure
The thyrohyoid muscle is a flat, triangular muscle that is located in the neck, just above the larynx. It is made up of two heads: a superior head that originates from the thyroid cartilage, and an inferior head that originates from the hyoid bone. The muscle fibers of the thyrohyoid muscle converge to form a tendon that inserts onto the hyoid bone.
The thyrohyoid muscle is innervated by the cranial nerve XII (the hypoglossal nerve). It is supplied by the superior thyroid artery, which is a branch of the external carotid artery.
There are a few variations of the thyrohyoid muscle that can occur in some individuals. These variations may include an additional head of origin, an extra muscle belly, or a division of the muscle into two distinct muscles. However, these variations are relatively rare and do not significantly affect the function of the muscle.
Location
The thyrohyoid muscle is located in the neck, just above the larynx. It is situated between the thyroid cartilage and the hyoid bone. The muscle is covered by the investing layer of the deep cervical fascia, which is a thin layer of connective tissue that covers and supports the muscles of the neck.
Function
The primary function of the thyrohyoid muscle is to move the larynx. When the thyrohyoid muscle contracts, it pulls the hyoid bone and the larynx upwards and towards the back of the throat. This movement helps to open the airway and allows for easier breathing.
In addition to its role in respiratory function, the thyrohyoid muscle also plays a role in the production of speech. When the thyrohyoid muscle contracts, it helps to tense the vocal cords and produce higher-pitched sounds.
Clinical significance
The thyrohyoid muscle can be affected by various medical conditions. For example, laryngospasm, which is a condition in which the larynx becomes narrowed or closed, can be caused by the spasm of the thyrohyoid muscle. This can lead to difficulty breathing and may require medical intervention.
Additionally, the thyrohyoid muscle may be affected by neck injuries, such as a fracture of the hyoid bone or a sprained neck. In these cases, the muscle may become strained or torn, leading to pain and difficulty moving the larynx.
