24.3 The Lower Respiratory System

• SUMMARY - The Larynx

  • Inhaled air passes through glottis to lungs; larynx surrounds and protects glottis. Epiglottis projects into pharynx.
  • Two pairs of folds span glottal opening: relatively inelastic vestibular folds and delicate vocal folds. Air passing through glottis vibrates vocal folds and produces sound.
  • The intrinsic laryngeal muscles regulate tension in vocal folds and open and close glottis. Extrinsic laryngeal muscles position and stabilize larynx. During swallowing, both sets of muscles help to prevent particles from entering glottis.
• What are the functions of the thyroid cartilage?

  The thyroid cartilage protects the glottis and the opening to the trachea.
• What is the function of the epiglottis?

  During swallowing, the epiglottis folds over the glottis, preventing food or liquids from entering the respiratory passageways.
• Laurel uses voluntary muscle contraction to shorten the distance between her thyroid and arytenoid cartilages. What happens to the pitch of her voice?

  The pitch of her voice gets lower.
• How would the absence of intrinsic laryngeal muscles affect swallowing?

  The glottis could not close without the intrinsic laryngeal muscles, so food or liquids could enter the respiratory passageways.