The thyroid cartilage with the Latin term Cartilago thyroidea represents the largest cartilage of the larynx. In English it is called Thyroid Cartilage. Outwardly, the thyroid cartilage is visible as an Adam's apple.
Especially in men Adam's apple appears prominently and forms the condition for a deep voice. The Adam's apple is one of the secondary male sexual characteristics. It forms through thickening of the thyroid cartilage under the influence of testosterone. Above the thyroid cartilage is the laryngeal lid (epiglottis), which prevents the passage of porridge into the trachea. The epiglottis is connected to the thyroid cartilage.
Below the Cartilago thyroidea sits the horizontal cricoid cartilage, which is articulated at the back with the arytenoid cartilages. The vocal cords or vocal cords stretch behind the thyroid cartilage. They are interconnected by arytenoid cartilage. The cohesion of cartilage is made by different ligaments, the larynx is hung by a membrane on the hyoid bone.
The thyroid cartilage is formed by two cartilaginous plates of hyaline cartilage. These cartilage plates are connected at the front in the middle. Towards the top there is a small notch in the cartilago thyroidea, which is called the incisura thyroidea superior.
From the outside she is even palpable. At the bottom there is a smaller inconspicuous notch called incisura thyroidea inferior. Behind the thyroid cartilage, the vocal cords are stretched between the arytenoid cartilages. The Cartilago thyroidea forms the anterior side of the larynx. He is still slightly arched forward. During puberty there is a thickening of this protrusion in the young men. It forms the typical Adam's apple, the voice is deeper. The thyroid cartilage is followed by four muscles.
The sternothyroid muscle represents a skeletal muscle that pulls down the thyroid cartilage. He starts with the linea obliqua, an oblique line structure of the thyroid cartilage. The thyrohyoid muscle is also located on the oblique line and is an extension of the sternothyroid muscle. By shortening the distance between the hyoid bone and the thyroid cartilage, it closes the larynx. As another pharyngeal muscle, the constrictor pharyngis inferior muscle lies furthest down in the direction of the esophagus. Part of the muscles, the pars thyropharyngea, begins again on the linea obliqua.
The other part, the cricopharyngeal pars, arises at the lateral margin of the cricoid cartilage. The constrictor pharyngis inferior muscle has two functions. On the one hand, he pushes the food porridge in the direction of the esophagus while swallowing, and on the other hand, he participates in the voice modulations. The cricothyroid muscle is the fourth muscle associated with thyroid cartilage. It begins at the cricoid cartilage and extends to the anterior border of the cartilago thyroidea. He is responsible for the regulation of the state of tension of the vocal cords and thereby increases the voice frequency.
The thyroid cartilage significantly determines the structure of the larynx and thus exerts a great influence on its function. Through his close connection to the laryngeal musculature and to the vocal cords, he is partly responsible for the closure of the larynx during swallowing and for voice training.
Structural changes of the thyroid cartilage, such as the formation of the Adam's apple, lead to a deeper voice due to this close connection. The individual muscles of the laryngeal muscles have, as already mentioned, different tasks. The thyroid cartilage, in addition to its function as an important structural component of the larynx, also ensures the fine-tuning of the various processes of voice formation. Even the smooth separation of the functions of the esophagus and trachea is partly due to the work of the thyroid cartilage.
Isolated diseases of the thyroid cartilage are very rare. Most of the Cartilago thyroidea in inflammation of the larynx (laryngitis) is affected, but not the cartilage, but only the mucous membrane is affected.
Laryngitis is often caused by viral infections. Rarer is a bacterial infection. However, inflammation due to autoimmune diseases is also possible. These processes mainly attack the mucous membranes. When the disease spreads to the vocal cords, there is hoarseness or even voice loss. There are also various benign and malignant laryngeal tumors. Benign tumors are more common than malignant tumors. Again, the thyroid cartilage is usually not isolated affected. A very common symptom is increased hoarseness.
The malignant forms are more than 90 percent squamous cell carcinoma. In turn, the cells of the mucosa degenerate. In rare cases, however, a chondrosarcoma may occur. In a chondrosarcoma degeneration of connective tissue cells of the cartilage occurs. Again, the localization is very rare, especially in the thyroid cartilage. Chemo- and radiotherapy are not successful in this tumor, because degenerated cartilage cells do not respond. The only chance of recovery results from the complete removal of the tumor.
This may mean that the larynx must be completely removed, resulting in loss of voice. If there is swelling under the thyroid cartilage, it may also be a thyroid disorder, in which a goitre develops. According to the symptoms, a superficial disease of the thyroid cartilage is suspected here. However, an adjacent organ is affected.