Pharynx and Larynx

Overview of the Pharynx

• Definition: The pharynx is a muscular tube extending from the base of the skull to around level C6, connecting the nasal cavity and mouth to the larynx and esophagus.

• Function: Acts as a pathway for both the respiratory and digestive systems.

Anatomy of the Pharynx

• Divisions:

  • Nasopharynx: Connects the nasal cavity to the pharynx.

  • Oropharynx: Connects the oral cavity to the pharynx.

  • Laryngopharynx: Connects larynx to the pharynx.

• Clinical Relevance: Understanding areas of the pharynx is important for procedures like the insertion of a nasogastric tube for feeding when oral intake is not possible.

Relationship Between Respiratory and Digestive Systems

• Trachea vs. Esophagus:

  • Trachea: Transports air to and from the lungs; only air should pass through.

  • Esophagus: Transports food and liquids to the stomach; only food and liquids should go down.

• Mechanism to Prevent Aspiration:

  • During eating, mechanisms ensure that food does not enter the trachea.

The Larynx

• Anatomical Position:

  • Anteriorly attached to the hyoid bone.

  • Connects to the laryngopharynx posteriorly.

• Purpose: Keeps the airway open and facilitates sound production.

Cartilage of the Larynx

• Key Structures:

  • Thyroid Cartilage: Recognizable "Adam's apple" at the front of the larynx.

  • Cricoid Cartilage: Located below the thyroid cartilage.

  • Thyrohyoid Membrane: Connects thyroid cartilage to hyoid bone.

  • Cricothyroid Ligament: Important for emergency airway procedures (e.g., Cricothyrotomy).

Epiglottis

• Function: A cartilage flap that covers the larynx during swallowing, preventing food from entering the airway.

• Clinical Importance: Helps prevent choking when swallowing. If food mistakenly enters the trachea, it triggers a cough reflex to expel it.

Vocal Cords

• Structure: Vocal cords (ligaments) are attached to arytenoid cartilages and thyroid cartilage.

• Function: Vibrate to produce sound when air passes from the trachea through them.

  • Sound Variation: Pitch and volume can change based on tension and airflow:

    • Higher tension = higher pitch.

    • Lower tension = lower pitch.

    • Loudness increases with higher pressure air.

• Types:

  • True Vocal Cords: Responsible for sound production.

  • False Vocal Cords (Vestibular folds): Assist with the protection of the larynx and help regulate sound production.

Conclusion

• Understanding the anatomy and functions of the pharynx, larynx, and associated structures is crucial for both clinical practices and the basic physiological processes of breathing and swallowing.