The morphological structure of the laryngeal cavity

Everyone knows that coughing is probably caused by inflammation in the patient's laryngeal cavity, so when treating, we must understand the morphology and structure of our laryngeal cavity. Especially for those college students studying medicine, they should learn this knowledge well to be responsible for themselves and future patients. When treating diseases, these are more important principles that need to be understood. So what is the morphology and structure of the laryngeal cavity?

The larynx connects to the laryngopharynx above and the trachea below, and is an important organ for breathing and pronunciation. Located in the middle of the front of the neck, it is equivalent to the 3rd to 6th cervical vertebrae in adults. It is a conical tubular organ composed of a group of cartilages, ligaments, laryngeal muscles and mucous membranes.

1. Laryngeal cartilage

The larynx is composed of three single cartilages - the thyroid cartilage, cricoid cartilage, and epiglottic cartilage; and three paired cartilages - the arytenoid cartilage, corniculate cartilage, and cuneiform cartilage.

1. Thyroid cartilage

The largest piece of cartilage in the laryngeal support is shaped like a book standing upright and half-opened backwards. The two sides are symmetrically connected by the thyroid cartilage wings that converge at the midline of the anterior neck to form a certain angle. The angle is smaller in men and the upper end protrudes forward, which is called the Adam's apple (thyroid notch). In women, the angle is approximately obtuse and the Adam's apple is not obvious. The posterior edges of the pterygoid plates of the thyroid cartilage on both sides extend upward and downward, forming small columnar protrusions, called the superior cornu and inferior cornu, respectively. The superior cornu is longer and is connected to the greater cornu of the hyoid bone by ligaments; the inferior cornu is shorter, and its medial surface forms the cricothyroid joint with the small depression on the posterior and lateral surface of the cricoid cartilage. There is a "V"-shaped depression in the middle of the upper edge of the thyroid cartilage, called the thyroid notch, which is a landmark for identifying the midline of the neck.

(ii) Cricoid cartilage

It is the only complete circular cartilage in the laryngeal and tracheal rings. It is the basis of the laryngeal support and is very important for supporting the patency of the laryngeal cavity and ensuring breathing. If the defect is caused by trauma, it often leads to laryngeal stenosis. The cricoid cartilage is located below the thyroid cartilage and connected to the trachea. The front part is narrower, called the cricoid arch, and the back part extends upward and is wider, called the cricoid plate (Figure 1-22).

3. Epiglottic cartilage

It is flat and leaf-like, with a free, arc-shaped upper edge and a stem at the lower end, attached to the inner surface of the anterior corner of the thyroid cartilage. The epiglottis is divided into the lingual surface and the laryngeal surface. The lingual surface has loose tissue and is therefore prone to swelling when infected. The epiglottis of infants and children is soft and curled, and bulges forward like an "Ω" or "∧" shape. In adults, it is mostly flat and hard.

(iv) Arytenoid cartilages

Also known as the sphenoid cartilage, it is located at the posterior and superior edge of the cricoid cartilage plate. It is in the shape of a triangular cone, one on each side, with the apex tilted posteriorly and medially. Its base is connected to the cricoid cartilage to form the cricoarytenoid joint. Its sliding and rotation on the articular surface can open or close the vocal cords. The front angle of the base is called the vocal process, to which the rear ends of the vocal cords attach. The lateral angle of the base is called muscular process

The cricoarytenoid process is the attachment point of the lateral cricoarytenoid muscle and the posterior cricoarytenoid muscle, and is responsible for the opening and closing of the glottis.