Overview
This lecture covers the key anatomical structures of the larynx, their relationships, and how to identify them on imaging—crucial for staging laryngeal cancers.
Main Components of the Larynx
- The larynx consists of cartilaginous and bony structures providing its external framework.
- The hyoid bone sits superiorly and supports the entire larynx via membranes.
- The epiglottis is a leaf-shaped structure that slants posteriorly, covering the larynx during swallowing.
- The thyroid cartilage forms the main bulk of the larynx, with an anterior laryngeal notch ("Adam’s apple").
- Superior and inferior horns of the thyroid cartilage articulate with adjacent structures.
- The cricoid cartilage is a complete ring, thicker posteriorly, and forms the base of the larynx.
- Thyrohyoid membrane connects the hyoid bone to the thyroid cartilage.
- Cricothyroid membrane lies between thyroid and cricoid cartilages, the site for emergency airway access.
Internal Structures & Folds
- Arytenoid cartilages sit atop the cricoid, controlling vocal cord movement.
- The vocal ligament spans from arytenoid to thyroid cartilage and forms the core of true vocal cords.
- The aryepiglottic fold connects the arytenoid cartilages to the epiglottis.
- False vocal cords (vestibular folds) sit above the true vocal cords, separated by the laryngeal ventricle.
- The laryngeal ventricle is an important landmark in cancer staging.
Relationships and Imaging Landmarks
- The vallecula is the space between the base of tongue and epiglottis.
- Median glossoepiglottic fold connects tongue base to epiglottis.
- Piriform sinuses are lateral to the larynx and part of the hypopharynx.
- Pre-epiglottic fat is seen just anterior to the epiglottis on CT.
Dynamic Function During Swallow
- Swallowing lifts the hyoid and thyroid cartilages, pushing the epiglottis down to cover the laryngeal inlet.
- Vocal cords close tightly, sealing the airway during swallowing.
- Soft palate elevates to prevent nasal regurgitation.
Laryngeal Regions for Cancer Staging
- Supraglottic: from epiglottis tip down to the top of the true vocal cords.
- Glottic: spans the true vocal cords.
- Subglottic: from below the true vocal cords to the lower edge of cricoid cartilage.
Key Terms & Definitions
- Hyoid bone — U-shaped bone at the top of the larynx for support.
- Epiglottis — Leaf-like cartilage that covers the airway during swallowing.
- Thyroid cartilage — Large cartilage with a laryngeal notch, forms main larynx structure.
- Cricoid cartilage — Complete cartilaginous ring at the base of the larynx.
- Arytenoid cartilages — Paired cartilages that move the vocal cords.
- Aryepiglottic fold — Mucosal fold between arytenoids and epiglottis.
- True vocal cords — Folds containing the vocal ligament, responsible for sound.
- False vocal cords — Folds above true vocal cords, not involved in sound.
- Laryngeal ventricle — Space between false and true vocal cords.
- Vallecula — Space between base of tongue and epiglottis.
- Piriform sinus — Space beside the larynx, part of hypopharynx.
Action Items / Next Steps
- Review CT and radiograph images to identify laryngeal structures.
- Learn boundaries of supraglottic, glottic, and subglottic regions for cancer staging.
- Await next lecture for laryngeal vascular, nerve supply, and muscular anatomy.