The larynx consists of nine cartilages, of which 3 are unpaired and 3 are coupled:
Unpaired cartilages: The unpaired cartilages are large and constitute:
Matched cartilages: The matched cartilages are small and constitute:
The primary cartilages of the larynx are, cricoid, thyroid and 2 arytenoids.
It acts as a shield to safeguard the larynx from the front and is most notable. It is composed of 2 quadrilateral laminae that meet in front with an angle referred to as thyroid angle, which is acute in males and obtuse in females (such as subpubic angle). The angle measures 90 ° in men and 120 ° in females.
The thyroid angle is notable in males and it is responsi-ble for visibility on the very front of the neck named Adam’s apple.
The posterior surface of the thyroid cartilage in the median plane gives connection (from above downward) to subsequent structures:
- Thyroepiglottic ligament.
- A pair of vestibular ligaments.
- A pair of vocal ligaments.
The posterior border of every lamina is free and extended upwards and downwards as superior and inferior horns/cornu. It gives conjoined insertion to the subsequent 3 muscles:
The outer surface of every lamina presents an oblique line and gives connection to the subsequent 3 muscles; from above downwards and from medial to lateral sides, these are as follows:
- Inferior constrictor (thyropharyngeus part only).
This is a signet-shaped ring of cartilage with a narrow anterior arch and a broad posterior lamina. The cricoid cartilage is situated in the level of C6 vertebra and entirely encircles the lumen of the larynx. It’s regarded as the foundation stone of the larynx. The posterior surface of lamina presents a median ridge and 2 depressed regions on every side of the ridge.
It’s leaf like and goes upward behind the hyoid bone and the base of the tongue. Its broad upper end is free and creates the upper boundary of the laryngeal inlet, while the lower end (stalk) is pointed and joined to the posterior outermost layer of the angle of the thyroid by thyroepiglottic ligament.
The anterior surface of epiglottis is joined with the base of the tongue by median and lateral glossoepiglottic folds. The depression on every side of the median fold is referred to as vallecula.
The posterior surface of epiglottis presents a tubercle in its lower part.
The epiglottis is vestigial in human beings but in macrosomatic creatures it’s elongated and goes past the soft palate in the nasopharynx.
- The matched arytenoid cartilages articulate with all the lateral parts of the upper border of cricoid lamina. Every arytenoid cartilage is pyramidal and presents an apex, base, 3 surfaces (posterior, anterolateral and medial) and 2 processes-muscular and vocal.
- The muscular process projects laterally and backwards on the other hand the vocal process is directed forwards.
- The base of arytenoid cartilage is concave and articulates with all the upper border of the lamina of cricoid cartilage. The base is prolonged anteriorly to create the vocal process and laterally to create the muscular process.
- The apex is arch posteromedially and articulates with the corniculate cartilage.
Corniculate Cartilages (of Santorini)
All these are 2 small conical nodules, which say with the apices of the arytenoid cartilages. They’re directed posteromedially and be located in the posterior parts of the aryepiglottic folds.
Cuneiform Cartilages (of Wrisberg)
They’re miniature rod shaped cartilages being located in the posterior parts of the aryepiglottic folds just above the corniculate cartilages.
Types of Laryngeal Cartilages
The thyroid, cricoid and basal parts of arytenoid cartilages are made up of hyaline cartilage and often ossify after 25 years old and can be viewed in radiographs.
The apices of arytenoid cartilages and other cartilages-epiglottis, corniculate and cuneiform are created from elastic cartilage and don’t ossify.