The cricoid cartilage (lat. : Cartilago cricoidea) is part of the thyroid cartilage, usually called the larynx. This is the transition from the pharynx to the trachea and part of the airway in the front of the throat. The thyroid cartilage, also part of the larynx, is visible as the Adam’s apple in the middle of the neck.
What is the cricoid cartilage?
The cartilago cricoidea, together with the thyroid and stellate cartilages and the epiglottis, forms the larynx. The cricoid cartilage itself is composed of hyaline cartilage: this is a form of cartilage that is particularly common in joints. Under the light microscope, these cartilages often have a bluish, milky color, but structures are not visible under the light microscope, unlike fibrocartilages, which is why the fibers of hyaline cartilages are called masked fibers. In addition, the vitreous cartilages are surrounded by a cartilage matrix, which is a protective tissue. The cricoid cartilage is also shaped like a signet ring and forms the part of the larynx that is lowest and close to the trachea. Directly below it is the tracheal cartilage. As the lowest part of the larynx, it carries the thyroid cartilage as well as the stellate cartilages.
Anatomy and structure
As hyaline cartilage, cricoid cartilage is ventrally directed, meaning that it faces the front of the body and may be externally visible. The cartilage itself is composed of the following parts:
- The anteriorly located arc of cricoid cartilage (lat. : Arcus cartilaginis cricoideae),
- The cricoid cartilage plate (lat. : Lamina cartilaginis cricoideae),
- Of a groin (crista mediana)
- And two articular surfaces (facies articularis thyroidea).
The arc of cricoid cartilage forms the cricoid cartilage plate by a thickening on the posterior side; This carries the centrally located groin, which has two articular surfaces, which are located on both sides and serve as a connection to the thyroid cartilage. The four individual parts and joints of the cricoid cartilage are connected by ligaments, these are also called the ligamentum cricothyroideum or ligamentum cricoarytenoideum. In addition, three following laryngeal muscles are located attached to the cricoid cartilage:
- The posterior cricoarytaenoideus muscle, or posticus for short,
- The lateral cricoarytaenoideus muscle.
- As well as the cricothyroid muscle.
The posticus is the outer surface of the lamina, known as the cricoid cartilage plate, and is part of the inner laryngeal muscles. The cricoarytaenoideus lateralis muscle is also part of the inner laryngeal musculature and forms the upper edge and the outer surface of the cricoid cartilage plate (arcus). The cricothyroid muscle forms the entire arcus and is thus part of the outer musculature of the larynx. In addition, the cricothyroid cartilage is connected to the inferior horn (cornu inferius) of the thyroid cartilage.
Function and tasks
As one of the three most important parts of the larynx, the cricoid cartilage is also responsible for the tasks that the larynx performs. The larynx is responsible for voice production (phonation): this occurs through the posticus, which originates at the cricoid cartilage and attaches to the muscular protrusion (processus muscularis) of a stellate cartilage. The muscular protrusion is pulled inward, causing the vocal folds to be pulled apart at the stellate cartilage. The pitch is determined by the frequency with which the air determines the vibrations of the voice. The amplification of the resonant chambers determines the volume; If the resonance of the lungs is stronger, or dominant, this is called the chest voice. The voice can change over time, for example during voice change: due to the increased production of the sex hormone testosterone in boys and estrogen in girls, the vocal cords begin to grow and thicken more quickly. This causes the vocal cords to vibrate more slowly and the voice to become deeper – Especially in boys, the voice can even drop an octave.
Diseases
Malformations of both the cricoid cartilage and the larynx in general occur extremely rarely, but are possible. Laryngeal atresia is a total closure (atresia) of the larynx that leads to death in most cases: Occlusion of the larynx results in the inability of oxygen to reach the trachea and causes severe breathing difficulties. Especially during pregnancy, laryngeal atresia is dangerous and can also lead to the so-called fetal CHAOS (Congenital High Airway Obstruction Syndrome). Very often, however, laryngitis can occur, known as laryngitis.They result from viral infections in the respiratory tract or, more rarely, from severe vocal stress in very dry rooms. Chronic laryngitis can develop due to alcohol and nicotine abuse, as well as permanent mouth breathing. Laryngitis can be manifested by hoarseness, but also often by voicelessness, accompanied by a strong, dry cough. Less common symptoms include fever up to 40 degrees and severe sore throat.
