What are the structures that compose the glottis?

Structures of the Glottis

The glottis is primarily composed of the true vocal folds (vocal cords) and the space between them. According to the European Respiratory Society (ERS), European Laryngological Society (ELS), and American College of Chest Physicians (ACCP) consensus, the glottis specifically refers to the true vocal folds and the space between them 1.

Anatomical Components of the Glottis

• True vocal folds - These are the primary structures of the glottis that vibrate during phonation to produce voice 1
• The glottis can be divided into two main portions:
  • Anterior glottis (membranous portion) - Contains the anterior portion of the true vocal folds 2, 3
  • Posterior glottis (cartilaginous portion) - Contains the posterior portion of the true vocal folds and the space between the arytenoid cartilages 2, 4

Dimensions and Proportions

• In human newborns, the posterior glottis accounts for approximately:
  • 56-57% of the entire glottic length 3
  • 68% of the entire glottic area 3
• In adults, the posterior glottis accounts for approximately:
  • 35-45% of the entire glottic length 4
  • 50-65% of the entire glottic area 4

Histological Characteristics

• Anterior glottis - Covered with stratified squamous epithelium 3
• Posterior glottis - Covered with respiratory (ciliated) epithelium, which supports its role in respiration 3, 4
• The lamina propria of the posterior glottis consists of two layers 4

Functional Significance

• The anterior glottis plays the most important role in phonation 3
• The posterior glottis has a significant role in respiration 3, 4
• During vocal fold adduction, the posterior part of the larynx closes completely not at the glottis but at the supraglottic level, forming a conic space in the posterior glottis that can only be viewed from below 4

Clinical Relevance

• Disorders affecting the glottis can lead to voice problems (dysphonia/hoarseness) 1
• Glottic insufficiency due to vocal fold weakness (paralysis or paresis) can result in a weak, breathy voice with poor cough and reduced airway protection during swallowing 1
• Obstructions at the glottic level can cause breathing problems and may be identified through laryngoscopy 1
• The shape of the glottis is not round but rather teardrop-shaped, which has implications for treatment approaches in conditions like posterior glottic stenosis 5

Surrounding Structures

• The glottis is bordered by:
  • Supraglottic structures - Including the arytenoid regions, epiglottis, and false vocal folds 1
  • Subglottic region - The area below the true vocal folds 2
• The false vocal folds (ventricular folds) are located above the true vocal folds and can influence glottal airflow and vocal fold vibration during phonation 6

Understanding the anatomical structure of the glottis is essential for proper diagnosis and management of laryngeal disorders, particularly those affecting voice production and breathing.