Aerodynamics of nasal breathing
The mechanics of air movement in the nasal cavity differ during inspiration and expiration. The respiratory reflex itself is triggered mechanically: the air jet stimulates the receptors of the mucous membrane.
- Mechanism of inspiration: The main flow rushes from bottom to top in an arc through the common nasal meatus, passes along the middle nasal concha, and turns downward toward the choanae. At this moment, part of the air contained within the paranasal sinuses (PNS) exits — this helps warm and humidify the cold inhaled flow.
- Mechanism of expiration: Air flows predominantly at the level of the inferior nasal concha. Simultaneously, part of the exhaled flow enters the sinuses, restoring their air volume.
Olfactory function
The olfactory analyzer is responsible for the chemical sense. Its adequate stimulus is molecules of odorous substances — odorivectors.
The peripheral division (regio olfactoria) begins at the olfactory cleft. To allow odors to reach this area, a person takes short, forced breaths (sniffing). This creates air vortices that direct odorivectors toward the receptors.
The molecules dissolve in the fluid covering the cilia of the olfactory cells. A nerve impulse is generated, which is transmitted to the cortical center of the analyzer, where higher analysis and synthesis of the odor take place. In science, there are three main theories of olfaction: chemical, physical, and physicochemical.
Pathophysiology of mouth breathing
Forced breathing through the mouth is a trigger mechanism for systemic disorders:
- Inspiration becomes shallow, and negative pressure in the chest decreases.
- Respiratory excursion of the lungs is reduced, and oxygen supply drops.
- Hypoxia develops, which is especially dangerous for children (affecting the nervous, vascular, and hematopoietic systems).
- Ventilation of the sinuses and middle ear cavities is locally impaired.
Furthermore, mouth breathing dries out the oral mucosa. This makes it harder to clean food debris from teeth, disrupts enamel nutrition, and alters the microbial landscape, leading to caries, stomatitis, and gingivitis. Reduced masticatory load provokes malposition of teeth and bite abnormalities.
Anatomical and physiological features in children
The structure of ENT organs at an early age determines the specifics of their diseases:
- Nasal cavity: The nasal passages are very narrow, and the inferior one is formed only by age 4. The mucous membrane is delicate, highly vascularized, and rich in secretory immunoglobulin A (sIgA). Even minimal edema during rhinitis causes complete obstruction, preventing infants from sucking milk properly.
- Bleeding: Cavernous (erectile) tissue in the submucosal layer is underdeveloped in infants, making nosebleeds rare. However, by 8–9 years of age, it actively proliferates, and against the background of vulnerable mucosa, bleeding becomes frequent.
- Paranasal sinuses: In newborns, the frontal sinuses are absent, while the maxillary, ethmoid, and sphenoid sinuses are rudimentary. They are fully formed only by age 15, which is why classic maxillary and frontal sinusitis practically do not occur in early childhood.
Common innervation and pain radiation
The upper respiratory tract, ear, and maxillofacial system share common sensory innervation. This frequently leads to cross-localization of pain, requiring collaborative work between the otolaryngologist and the dentist.
- Toothache may be the result of inflammation of the external auditory canal or a tumor process in the maxillary sinus.
- Ear, throat, or nose pain often arises due to dental problems: glossitis, salivary gland inflammation, or temporomandibular joint (TMJ) arthritis.
To remember nasal aerodynamics, imagine a fountain: during inspiration, the jet arches upward (along the middle concha), while during expiration, water flows down the lower level (along the inferior concha).
Class and exam questions
What is the difference between the conducting zone and the respiratory division?
The conducting zone (from the nose to the bronchioles) only delivers, warms, and cleans the air. Gas exchange (external respiration) occurs exclusively in the respiratory division — the alveoli.
Why does chronic nasal breathing obstruction in children alter facial appearance?
Due to hypertrophy of the pharyngeal tonsil (adenoids), the child breathes through the mouth constantly. This disrupts the development of the facial skeleton and creates an "adenoid face" (facies adenoidea): a chronically semi-open mouth and characteristic puffiness.
Can diseased teeth cause ENT diseases?
Yes, dental and periodontal diseases very frequently cause inflammatory processes in the maxillary sinus due to their anatomical proximity.
What else to study on this topic
- Congenital malformations (cleft lip and palate, ear and TMJ anomalies)
- Dynamics of development of the lymphoid pharyngeal ring (Waldeyer's ring)
- Congenital muscular anomalies (torticollis, diaphragmatic defects)
- Methodology for collecting ENT anamnesis and assessing the patient's objective status
- System-based physical examination for ENT pathologies
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