Larynx


Label 1-7

  • 1 – epiglottis
  • 2 – hyoid bone
  • 3- thyroid cartilage
  • 4- cricoid cartilage
  • 5 – arytenoid cartilage
  • 6 – cuneiform cartilage
  • 7 – corniculate cartilage

What membrane joins 2 and 3?

  • Thyrohyoid membrane

What ligament joins 3 and 4?

Cricothyroid membrane

Supporting Information

Anatomy of the larynx

The skeleton of the larynx consists of the laryngeal cartilages which calcify during puberty:

  • Hyaline– thyroid, cricoid and arytenoid, corniculate, cuneiform
  • Fibrocartilage– epiglottis 
  • Fibroelastic accessory cartilage  

The larynx is split into 3 parts:

  1. Supraglottis- laryngeal surface epiglottis, aryepiglottic folds, vestibular folds, laryngeal ventricles as the superior surface vocal folds. 
  2. Glottis- vocal folds and 1cm inferior
  3. Subglottis– down to lower border cricoid

Vocal cord layers (superficial to deep):

  • stratified squamous epithelium
  • Reinke’s space (superficial lamina propria)
  • Vocal ligament (intermediate and deep lamina propria)
  • Thyroarytenoid/vocalis muscle

Muscles of the larynx- controlled by internal and one external muscle (cricothyroid)

Action

Muscles

Cord abduction

Posterior crico-arytenoid

Cord adduction

Lateral cricoarytenoid muscle

Transverse arytenoid muscle

Oblique arytenoid

Vocal cord tension

Cricothyroid

Thyroarytenoid

Nerve supply of the larynx

This is by the vagus nerve (CN X) – Splits into:

  • Superior laryngeal nerve- 
    1. Internal branch- sensory- supraglottis and superior aspect vocal cords 
    2. External branch- motor- cricothyroid muscle
  1. Recurrent laryngeal nerve- left one loops around the arch of the aorta and travels in tracheoesophageal groove. Right one loops under the right subclavian and into the tracheoesophageal groove. Both enter at the inferior cornu of the thyroid cartilage. 
    1. Sensation to larynx inferior to glottis and inferior aspect of vocal cords
    2. Motor to all other laryngeal muscles

Arteries and the relations to the nerves:

  • Superior thyroid- external carotid- enters at the superior pole of thyroid. Early in path it lies close to superior laryngeal nerve
  • Inferior thyroid artery – thyrocervical trunk- bends medial at C6 and enters lower thyroid pole. Both sides lie close to the recurrent nerve. 
    • RLN anterior to artery- 25%
    • RLN posterior to artery – 35%
    • RLN between branches of artery- 35%
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