Anatomy of the Nasopharynx and Oropharynx

Anatomy of the Larynx and Airway Management

• The superior thyroid notch and laryngeal prominence (Adam's apple) are vital landmarks for airway techniques and laryngeal nerve blocks.
• Cricoid cartilage marks the larynx's inferior limit and connects to the thyroid cartilage via the cricothyroid membrane, functioning as the only complete cartilaginous ring in the airway.
• Arytenoid cartilages articulate with the posterior cricoid, serving as attachments for the vocal cords.
• The epiglottis, a cartilaginous flap, acts as the anterior border of the laryngeal inlet, directing food away during swallowing.
• Hyoepiglottic ligament connects the anterior surface of the epiglottis to the hyoid bone.
• Laryngeal cavity lies below the laryngeal inlet, extending to the cricoid cartilage and contains ventricular and true vocal cords.
• Glottis refers to the space between the vocal cords, while the vestibule is above and the subglottis is below the vocal cords.

Structure and Function of the Trachea

• Trachea begins at the cricoid cartilage and ends at the carina at the fifth thoracic vertebra, measuring 10 to 15 cm in adults.
• It consists of 16 to 20 C-shaped cartilaginous rings, which are interconnected by fibroelastic tissue, with the trachealis muscle forming the posterior wall.
• At the carina, the trachea bifurcates into right and left mainstem bronchi; the right bronchus is more vertically oriented, increasing aspiration risk.

Predicting Airway Difficulties

• Anesthesiologists should anticipate possible airway management challenges based on patient history and physical findings.
• Previous difficulty with intubation is a strong predictor of future issues; a history of easy intubation does not guarantee future ease.
• Key assessments include evaluating patient weight, symptoms, pathological conditions, and obtaining previous anesthetic records.

Evaluation Techniques for Airway Assessment

• Traditional airway assessment may include methods like the Mallampati score, which can be improved with additional measurements (thyromental, sternomental distances).
• Multivariable assessments, such as the Wilson risk sum score and the El-Ganzouri risk index, enhance predictive accuracy.
• Apneic oxygenation allows oxygen to diffuse into alveoli during apnea, extending the safe duration for anesthesia without desaturation.

New Approaches to Airway Management

• THRIVE (Transnasal Humidified Rapid-Insufflation Ventilatory Exchange) can provide higher flow rates, improving oxygenation and carbon dioxide clearance during apnea.
• Various techniques (e.g., nasal cannula, pharyngeal oxygen insufflation) can help delay desaturation in patients with difficult airways.

Components of the Pharynx

• The nasopharynx ends at the soft palate and commonly experiences airway obstruction when adenoid tonsils are enlarged.
• Oropharynx features the palatoglossal and palatopharyngeal folds and houses tonsils, potentially leading to obstruction.
• Valleculae are paired spaces bounded by glossoepiglottic folds located in the anterior oropharynx.

Laryngeal Anatomy Overview

• Larynx consists of nine cartilages: thyroid, cricoid, arytenoid (paired), corniculate, cuneiform, and epiglottis.
• Cartilages are connected by ligaments and membranes, suspended by the hyoid bone via thyrohyoid ligaments.
• Thyroid cartilage is the largest and supports surrounding soft tissues of the larynx, facilitating functions such as phonation and airway protection.

This quiz covers the anatomy of the nasopharynx and oropharynx, including the role of adenoid tonsils and their impact on airway obstruction. Understanding these structures is essential for managing airway devices in patients. Test your knowledge on the features and functions of these important anatomical regions.