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The larynx contains various unpaired cartilages. There are three unpaired laryngeal cartilages: the cricoid cartilage, thyroid cartilage, and epiglottic cartilage.
CRICOID CARTILAGE
The cricoid cartilage is known as the ring-like structure of the larynx. It is located near the center and middle of the neck and surrounds the trachea. This sits on a plane below the thyroid gland and thyroid cartilage. This is also the most inferior laryngeal cartilage. It mainly functions to maintain airway patency and provide an attachment point to the other structures (Saran, 2021).
The following are the landmarks of the cricoid cartilage:
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ANTERIOR CRICOID ARCH
Compared to other landmarks, this is thinner in width. This provides clearance and enables the movement of the vocal folds.
POSTERIOR QUADRATE LAMINA
This provides elevation to the cricoid cartilages posteriorly.
ARTICULAR FACETS
This forms the cis the point of articulation for the inferior horns of the cartilage. The facet for arytenoid allows the cricoid cartilage to articulate with the arytenoid.
CRICOTHYROID JOINT
The cricothyroid joint is a synovial joint taht permits rotation and allows the backward and forward rocking movement of the cricoid and thyroid cartilages
THYROID CARTILAGE
The thyroid cartilage is a hyaline cartilage and is the largest laryngeal cartilage. This inferiorly articulates with the cricoid. This also contains the infamous Adam's Apple (scientifically and medically known as the laryngeal prominence). It has a V-Shaped body and has an anterior connection point and no posterior connection points.
While the circoid cartilage allows rotation, the thyroid cartilage allows the rocking motion. This directly protects the parts of the vocal folds directly behind it. Moreover, it is important to note that a change in pitch occurs when there is a change in the position of the thyroid cartilage relative to the cricoid cartilage (Saran, 2021).
The following are the landmarks of the thyroid cartilage:
Image sources:
https://www.slideshare.net/AbbasALRobaiyee1/head-and-neck-anatomy-19
https://www.slideshare.net/MehulTandel/larynx-dr-mehul-tandel
Thyroid notch - This is the most superior portion and is also known as the Adam's Apple. This is more prominent in males than in females.
Oblique line - This marks the attachment of two musculature and is the lateral superficial aspect of the thyroid lamina.
Inferior cornua - This projects inferiorly to articulate with the cricoid cartilage
Superior cornua - This projects superiorly to articulate with the hyoid.
EPIGLOTTIS
The epiglottis is an elastic leaf-like structure that is entirely covered by mucosa. It projects posteriorly and superiorly to the pharynx. It functions to protect the larynx from food and other substances especially during swallowing. It attaches to the hyoid bone through the hyoepiglottic ligament and to the thyroid cartilage through the midline thyroepiglottic ligament.
The landmarks of the epiglottis are as follows:
Hyoepiglottic ligament - As mentioned, this attaches the epiglottis to the hyoid bone. This protects the preepiglottic and paraepiglottic spaces. This also separates the tongue base and the supraglottic larynx. This includes the epiglottis and part of the aryepiglottic folds.
Glossoepiglottic folds - This is formed by the anterior or lingual surface of the epiglottis being curved forward.
Valeculae - These are very important landmarks in swallowing.
image source: https://www.slideshare.net/MehulTandel/larynx-dr-mehul-tandel
Other important notes about the epiglottis:
The CRANIAL NERVE X or the VAGUS NERVE conducts sensory information to the larynx (with/ through the epiglottis).
The epiglottis has two subdivisions: the suprahyoid subdivision which is visible and has a free anterior surface and the infrahyoid subdivision which is not free and not exposed.
The epiglottis also has two surfaces: the lingual surface which faces the tongue and the laryngeal surface which faces the larynx.
REFERENCES:
Barnes, S. (2019). Laryngeal Ligaments and Folds - Vocal - Vestibular - TeachMeAnatomy. TeachMeAnatomy. https://teachmeanatomy.info/neck/viscera/larynx/ligaments-folds/
Fuller, D. R., Pimentel, J. T., & Peregoy, B. M. (2012). Applied anatomy & physiology for speech-language pathology & audiology. Wolters Kluwer/Lippincott Williams & Wilkins Health.
Saran, M., Georgakopoulos, B., & Bordoni, B. (2021). Anatomy, Head and Neck, Larynx Vocal Cords. PubMed. https://www.ncbi.nlm.nih.gov/books/NBK535342/
Seikel, J. A., Drumright, D. G., & Seikel, P. (2013). Essentials of anatomy & physiology for communication disorders. Delmar Cengage Learning.
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