upperrespiratory

The upper respiratory tract refers to the portion of the respiratory system that conducts air from the outside environment toward the lower airways. In most anatomical classifications it includes the nose and nasal cavities, the paranasal sinuses, and the pharynx; many sources also include the larynx as part of the upper airway, while others place it in the lower tract. This region plays a key role in preparing inspired air for the lungs and in protecting the lower respiratory system from inhaled pathogens and irritants.

Anatomy and structure: The nasal cavity is lined by a mucous membrane with ciliated epithelium and goblet cells, producing mucus that traps particles. Turbinates increase surface area and aid in warming, humidifying, and filtering air. The paranasal sinuses are air-filled spaces that also participate in conditioning air and in resonance of the voice. The pharynx connects the nasal and oral cavities to the larynx and esophagus and is divided into the nasopharynx, oropharynx, and laryngopharynx. The larynx, when considered part of the upper airway, contains the vocal folds and contributes to voice production and airway protection.

Physiology and function: The upper tract filters particles, pathogens, and allergens, humidifies and warms inspired air, and participates in olfaction and voice resonance. Mucociliary clearance moves trapped material toward the pharynx for swallowing. The nasal cycle can cause periodic fluctuations in nasal airflow.

Clinical relevance: The upper tract is a common site of infections and inflammatory conditions, including rhinitis, sinusitis, pharyngitis, and tonsillitis, often viral in origin. Allergic rhinitis and chronic rhinosinusitis are notable noninfectious conditions. Management emphasizes symptomatic relief, infection control, allergy management, and, when appropriate, vaccination and avoidance of triggers. Complications can include spread to the lower respiratory tract or secondary bacterial infections.