Vocal Fold Structure and Function

Vocal Fold Structure and Function

Vocal Fold Structure and Function

On this page

Vocal Fold Anatomy - Anatomy Unlayered

  • Paired mucosal folds within the larynx, crucial for phonation (voice production).
  • Extend from thyroid cartilage (anteriorly) to arytenoid cartilages (posteriorly).
  • Length: Adult males 17-23 mm; adult females 12-17 mm.
  • Layers (Hirano's Body-Cover Theory): 5 distinct histological layers, grouped into 3 functional sections.
    • Cover (Vibratory segment):
      • Epithelium: Stratified squamous, non-keratinized.
      • Superficial Lamina Propria (SLP) / Reinke's Space: Gelatinous, highly pliable. 📌 Site of Reinke's Edema.
    • Transition (Vocal Ligament - provides resilience):
      • Intermediate Lamina Propria (ILP): Elastic fibers.
      • Deep Lamina Propria (DLP): Collagenous fibers.
    • Body (Muscular core - provides bulk & tension):
      • Thyroarytenoid (Vocalis) Muscle.
  • Glottis: Airway space between the true vocal folds. Vocal fold tissue layers

⭐ Reinke's Space (SLP) is the primary vibrating layer; its condition critically impacts voice quality. Fluid accumulation (edema) here is common.

Phonation Physiology - Voice Mechanics

  • Myoelastic-Aerodynamic Theory: Voice production via interplay of muscle (myoelastic) & airflow (aerodynamic) forces.
    • Vocal folds (VFs) adduct (LCA, IA muscles).
    • Subglottic pressure ($P_{sub}$) builds.
    • $P_{sub}$ overcomes glottic resistance → VFs open (inferiorly then superiorly).
    • Air puff released, $P_{sub}$ drops.
  • Bernoulli Principle: ↑ airflow velocity in constricted glottis → ↓ pressure.
    • This negative pressure sucks VFs medially, aiding closure (inferiorly first).
  • Mucosal Wave: Rippling of VF mucosa over the vocalis muscle.
    • Essential for clear, resonant voice; assessed by stroboscopy.
    • Reduced/absent in VF stiffness (e.g., scar, sulcus).

⭐ The myoelastic-aerodynamic theory is the most widely accepted model explaining voice production, highlighting the interplay of muscle tension, elasticity, and airflow.

Innervation & Blood Supply - Power & Pipes

  • Innervation (Vagus Nerve - CN X):

    • Superior Laryngeal Nerve (SLN):
      • Internal br: Sensory to supraglottic mucosa (cough reflex).
      • External br: Motor to Cricothyroid m. (VF tensor, ↑pitch).
    • Recurrent Laryngeal Nerve (RLN):
      • Motor: All intrinsic laryngeal muscles (except Cricothyroid); controls VF abduction/adduction.
      • Sensory: Infraglottic mucosa & vocal folds.
      • 📌 L RLN longer (aortic arch); R RLN (subclavian a.).

      ⭐ Cricothyroid m. (pitch elevation) is the sole muscle innervated by External SLN.

  • Blood Supply:

    • Arteries:
      • Sup. Laryngeal A. (from Sup. Thyroid A.): Supraglottis; with Int. SLN.
      • Inf. Laryngeal A. (from Inf. Thyroid A.): Infraglottis; with RLN.
    • Veins:
      • Veins parallel arteries: drain to Sup. Thyroid V. (→IJV), Inf. Thyroid V. (→Brachiocephalic V.).

Laryngeal innervation and vascular supply

High‑Yield Points - ⚡ Biggest Takeaways

  • Vocal folds: 5 layers (Epithelium, Superficial LP/Reinke's space, Intermediate LP, Deep LP, Vocalis muscle).
  • Reinke's space (Superficial LP): key for mucosal wave; site of Reinke's edema.
  • Vocal ligament: formed by Intermediate and Deep Lamina Propria.
  • RLN innervates most intrinsic muscles; SLN (External branch) innervates Cricothyroid.
  • Cricothyroid tenses folds, ↑ pitch; Vocalis muscle forms the fold's body.
  • Voice production relies on Myoelastic-Aerodynamic theory & Bernoulli effect.

Practice Questions: Vocal Fold Structure and Function

Test your understanding with these related questions

A patient presents with hoarseness and laryngoscopy reveals a warty, cauliflower-like growth on the vocal cord. Identify the most likely lesion.

1 of 5

Flashcards: Vocal Fold Structure and Function

1/9

Treatment of adductor dysphonia consists of botulinum toxin injections in the _____ muscle (external part) on one or both sides to relieve spasm.

TAP TO REVEAL ANSWER

Treatment of adductor dysphonia consists of botulinum toxin injections in the _____ muscle (external part) on one or both sides to relieve spasm.

thyroarytenoid

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial