Cricoid cartilage

Of the Cricoid cartilage (lat .: Cartilago cricoidea) is part of the thyroid cartilage, usually called the larynx. This is the transition from the throat to the windpipe and part of the airway in the front of the neck. The thyroid cartilage, also part of the larynx, is visible as an Adam's apple in the center of the neck.

What is the cricoid cartilage?

The cartilago cricoidea forms the larynx together with the thyroid cartilage and the adjusting cartilage as well as the epiglottis.

The cricoid cartilage itself consists of a hyaline cartilage: This is a form of cartilage that is particularly often found in joints. In the light microscope, these cartilages often have a bluish, milky color, but in contrast to fiber cartilage, structures cannot be seen with light microscopy, which is why the fibers of the hyaline cartilage are referred to as masked fibers. In addition, the glass cartilage is 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 closest to the windpipe. The tracheal cartilage lies directly below it. As the lowest part of the larynx, it bears the thyroid and control cartilages.

Anatomy & structure

As hyaline cartilage, the cricoid cartilage is directed ventrally, which means that it points to the front of the body and is possibly externally visible. The cartilage itself consists of the following parts:

• the anterior cricoid cartilage arch (lat .: Arcus cartilaginis cricoideae),
• the cricoid cartilage plate (lat .: Lamina cartilaginis cricoideae),
• a groin (crista mediana)
• as well as two articular surfaces (facies articularis thyroidea).

The cricoid cartilage arch forms the cricoid cartilage plate through a thickening on the rear side; This carries the centrally located bar, which has two joint surfaces that lie 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 known as the cricothyroid ligament or the cricoarytenoid ligament. There are also three of the following larynx muscles attached to the cricoid cartilage:

• The cricoarytaenoideus posterior, or posticus for short,
• the lateral cricoarytaenoideus muscle
• and the cricothyroid muscle.

The posticus is the outer surface of the lamina, known as the cricoid plate, and is part of the internal muscles of the larynx. The cricoarytaenoideus lateralis muscle is also part of the inner larynx muscles and forms the upper edge as well as the outer surface of the cricoid arch (arcus). The cricothyroid muscle forms the entire arc and thus belongs to the outer muscles of the larynx. In addition, the cricoid cartilage is connected to the lower horn (cornu inferius) of the thyroid cartilage.

Function & 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 the formation of the voice (phonation): This takes place through the posticus, which arises from the cricoid cartilage and attaches to the muscle protrusion (processus muscularis) of an adjusting cartilage. The muscle protrusion is pulled inwards, which pulls the vocal folds apart on the adjusting cartilage. The pitch is determined by the frequency with which the air determines the vibrations of the voice. The amplification of the resonance chambers determines the volume; If the resonance of the lungs is stronger or dominates, this is called the chest voice.

The voice can change over time, for example when the voice breaks: Due to the increased production of the sex hormone testosterone in boys and estrogen in girls, the vocal cords begin to grow and thicken faster. 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 occlusion (atresia) of the larynx, which in most cases leads to death: an occlusion of the larynx prevents oxygen from entering the windpipe and causes severe breathing difficulties. Laryngeal atresia is particularly dangerous during pregnancy and can also lead to so-called fetal CHAOS (Congenital High Airway Obstruction Syndrome).

Very often, however, laryngitis, known as laryngitis, can occur. They result from viral infections in the respiratory tract or, more rarely, from strong voice strain in very dry rooms. Chronic laryngitis can develop from alcohol and nicotine abuse, as well as from persistent mouth breathing.

Laryngitis can manifest itself as hoarseness, but also often as voicelessness, accompanied by a strong, dry cough. Less common symptoms include a fever of up to 40 degrees and a severe sore throat.