As the first segment of the lower airway, the trachea is the air-conducting connector between the larynx and the bronchi. Air reaches the lungs through the trachea. If food enters the trachea instead of the esophagus as a result of eating too hastily, this causes a strong coughing impulse that is accompanied by a spasm of the tracheal muscles and is probably familiar to most people.
What is the trachea?
The trachea attaches to the larynx and ends at the level of the sternum, so it extends from the neck into the chest cavity. Typically, the trachea is between 10 and 15 cm long and about 15 to 25 mm in diameter. The elastic wall of the trachea, also called the trachea, consists of connective tissue and layers of smooth muscle. Cartilaginous clasps in the anterior wall provide stability and strength to the trachea.
Anatomy and structure
The muscular tube of the trachea divides at the level of the 4-5 thoracic vertebrae into the right and left main bronchus, and at the upper end it connects to the cricoid cartilage of the larynx. At the branching point, the tracheal fork, there is a spur called the carina trachea, which is important in dividing the air between the right and left main bronchus. The trachea is located in front of the esophagus and behind the thyroid gland. It owes its strength to the 16-20 cartilaginous clasps in the anterior wall, which are connected by annular ligaments. The elastic tissue between the cartilaginous clasps is important to allow the trachea to stretch and shift when swallowing or moving the head. While the cartilage clasps with the ligaments are on the front side, there is smooth muscle and connective tissue on the back side. The tracheal muscles can narrow the trachea by up to 25% of its original diameter. The inner wall of the trachea is lined with ciliated epithelium. Because of the ciliated epithelium and the mucus produced by the goblet cells, foreign bodies such as dust can be transported out of the trachea and coughed up or swallowed.
Functions and tasks
The main function of the trachea is to transport gas, that is, to conduct air from the throat area to the lungs. In addition, the air in the trachea is warmed, moistened, and cleared of foreign bodies with the help of the ciliated epithelium. The inner wall of the trachea is densely packed with ciliated hairs and goblet cells, which secrete mucus. The cilia move the dust particles and other foreign bodies bound in the mucus toward the pharynx. If an inhaled foreign body is too large to be transported out of the trachea in this way, a strong cough reflex sets in. This causes the foreign body to be coughed out. The cartilaginous braces that enclose the front of the trachea have a stabilizing function. During inhalation, a negative pressure is created which would cause the elastic trachea to collapse without stabilizing elements. The cartilage braces therefore ensure that inhalation is possible without the trachea closing or collapsing due to the negative pressure. The elasticity of the trachea is particularly important. During the swallowing process, the larynx regularly moves upward and the trachea must be able to follow this movement without any problems. When the cough reflex sets in, even more elasticity is demanded of the trachea, as it must also stretch in the longitudinal direction. The inside of the trachea is a mucous membrane under which trachea glands are located for additional moistening, which, like the goblet cells also, form mucus.
Diseases
A wide variety of problems related to the trachea can occur. Aspiration of a foreign body is particularly common, causing a severe coughing episode. If an inhaled foreign body cannot be coughed up, death from suffocation is imminent, and emergency measures such as a tracheotomy become necessary. The most common disease associated with the trachea is trancheitis, an inflammation of the trachea. This can be caused by an infection with bacteria or viruses but can also occur due to an allergy and leads to pain when swallowing and coughing with sputum. In tracheal stenosis, the trachea is narrowed, which can lead to shortness of breath and can be detected by altered breathing sounds, such as whistling or humming. Injuries to the trachea due to accidents often require surgical treatment.In tracheomalacia, the trachea collapses during inhalation because the cartilage clasps do not adequately support the trachea. Symptoms of tracheomalacia include difficulty breathing, hoarseness, and pathologic breath sounds.
Typical and common disorders
- Tracheitis
- Difficulty swallowing
- Tracheal stenosis
