The thyroarytenoid muscle is a broad, thin muscle that forms the body of the
vocal fold
The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound product ...
and that supports the wall of the ventricle and its appendix. It functions to shorten the vocal folds.
Structure
It arises in front from the lower half of the angle of the
thyroid cartilage
The thyroid cartilage is the largest of the nine cartilages that make up the ''laryngeal skeleton'', the cartilage structure in and around the trachea that contains the larynx. It does not completely encircle the larynx (only the cricoid cartilage ...
, and from the
middle cricothyroid ligament
The cricothyroid ligament (also known as the cricothyroid membrane or cricovocal membrane) is a ligament in the neck. It connects the cricoid cartilage to the thyroid cartilage. It prevents these cartilages from moving too far apart. It is cut d ...
.
Its fibers pass backward and laterally, to be inserted into the base and anterior surface of the
arytenoid cartilage.
Parts
The lower and deeper fibers of the muscle can be differentiated as a triangular band which is inserted into the vocal process of the arytenoid cartilage, and into the adjacent portion of its anterior surface; it is termed the ''Vocalis'', and lies parallel with the
vocal ligament
In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speec ...
, to which it is adherent.
[Frank H. Netter, MD "Atlas of Human anatomy", 7th Edition, 2019, Plate 91, superior view]
The vocal muscle is the upper portion of the thyroarytenoid muscle which is primarily involved in producing speech.
A considerable number of the fibers of the thyroarytenoid muscle are prolonged into the
aryepiglottic fold
The aryepiglottic folds are triangular folds of mucous membrane of the larynx. They enclose ligamentous and muscular fibres. They extend from the lateral borders of the epiglottis to the arytenoid cartilages, hence the name 'aryepiglottic'. They ...
, where some of them become lost, while others are continued to the margin of the epiglottis. They have received a distinctive name,
thyroepiglottic muscle
A considerable number of the fibers of the thyroarytenoid muscle are prolonged into the aryepiglottic fold
The aryepiglottic folds are triangular folds of mucous membrane of the larynx. They enclose ligamentous and muscular fibres. They extend ...
, ''thyreoepiglotticus'' or ''thyroepiglottic'', and are sometimes described as a separate muscle.
A few fibers extend along the wall of the ventricle from the lateral wall of the
arytenoid cartilage to the side of the epiglottis and constitute the ''ventricularis'' muscle.
Function
The thyroarytenoid muscle, consisting of two parts having different attachments and different directions, is rather complicated as regards its action.
Its main use is to draw the arytenoid cartilages forward toward the thyroid, and thus relax and shorten the vocal folds.
But, owing to the connection of the deeper portion with the vocal fold, this part, if acting separately, is supposed to modify its elasticity and tension, while the lateral portion rotates the arytenoid cartilage inward, and thus narrows the
rima glottidis
The rima glottidis is the opening between the two true vocal cords anteriorly, and the two arytenoid cartilages posteriorly. It is part of the larynx.
Anatomy
The rima glottidis is the narrowest part of larynx. It is longer (~23 mm) in males ...
by bringing the two vocal folds together.
Additional images
File:Gray959.png, Muscles of larynx. Side view. Right lamina of thyroid cartilage removed.
File:Vocalis muscle.JPG, Cross sectional cut of vocalis muscle
References
External links
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Muscles of the head and neck