LARYNX

Q.1 What is the extent of the larynx?

From root of tongue to trachea. In front of C3-5 vertebra.

Q.2 Name the cartilages forming the skeletal framework of the larynx.

Unpaired:

• Thyroid,
• Cricoid and
• Epiglottic.

Paired:

• Arytenoid,
• Corniculate and
• Cuneiform
  
  

Q.3 What is Adam’s apple?

Also called laryngeal prominence. It is formed by the fusion of anterior borders of the lamina of the thyroid cartilage. It is more prominent in males.

Q.4 Name the structures attached to the oblique line of the thyroid cartilage.

Sternothyroid, Thyrohyoid and Inferior constrictor

Q.5 What is the histological type of laryngeal cartilages?

Thyroid, cricoid, and bases of arytenoid: Hyaline
Ossify after 25 years of age.

Rest: Fibrocartilage
Never ossify.

Q.6 What are different laryngeal joints and what are their movements?

• Cricothyroid joint: Synovial joint.
  Between inferior cornu of the thyroid cartilage and lateral side of arch of cricoid.
  Rotatory movements around the transverse axis and gliding movements.
  
  
• Cricoarytenoid joint: Synovial joint.
  Between the base of the arytenoid and upper border of cricoid.
  Rotatory movements around a vertical axis and gliding movements.
  
  

Q.7 Name laryngeal ligaments and membranes.

• Thyrohyoid membrane thickens to form median and lateral thyrohyoid ligament
• Cricotracheal ligament
• Thyroepiglottic ligament
• Anterior cricothyroid ligament
• Hypoepiglostic ligament
• Cricovocal membrane
• Vocal ligament.
  
  

Q.8 What are the boundaries of the inlet of the larynx?

Anterior: Epiglottis

Posterior: Inter-arytenoid fold of mucous membrane

On each side: Aryepiglottic fold.

Q.9 Name the cartilages lying within aryepiglottic fold.

Corniculate and cuneiform cartilages.

Q.10 What are the parts of the larynx?

• Vestibule of larynx: Lying above vestibular folds
• Sinus of larynx: Between vestibular and vocal folds
• Infraglottic part: Below vocal folds.
  
  

Q.11 What is the characteristic feature of the laryngeal mucous membrane?

• Anterior surface and upper 1/2 of the posterior surface of the epiglottis, upper parts of aryepiglottic folds, and vocal folds are lined by stratified squamous epithelium.
  Rest of the laryngeal mucous membrane is covered with columnar ciliated epithelium.
• Mucous membrane is loosely attached except to vocal ligament and posterior surface of epiglottis.
• Mucous glands are absent over vocal cord.
  
  

Q.12 Name the intrinsic muscles of the larynx?

Muscles that open or close the inlet of the larynx: – Oblique arytenoids: Closes the inlet of larynx. – Thyroepiglottic: Opens the inlet of larynx. – Aryepiglottic: Closes the inlet of larynx.

Muscles that open or close the glottis: – Posterior cricoarytenoid: Opens glottis. Both anterior and posterior triangular part, wide open in forced respiration. – Lateral cricoarytenoid: In whispering, the anterior part of the glottis is closed but the posterior part in open. – Transverse crico-arytenoid: During the speech, both vocal fold and arytenoid cartilage are close together.

Muscles that increase or decrease the tension of vocal fold: – Cricothyroid: Tense the vocal fold – Thyroarytenoid: Relax the vocal fold – Vocalis: Tenses the vocal fold. Also called as tuning fork of larynx.

 

Q.13 Which intrinsic muscle of larynx is unpaired?

Transverse arytenoid

Q.14 What is the nerve supply of larynx?

Motor:
Cricothyroid: External laryngeal nerve

Other intrinsic muscles: Recurrent laryngeal nerve.

Sensory:
Mucous membrane up to vocal cord: Internal laryngeal nerve.

Mucous membrane below the vocal cord: Recurrent laryngeal nerve.

Q.15 What is the effect of lesion of ‘external laryngeal nerve’?

Weakness of phonation due to loss of tightening effect of cricothyroid on vocal cord.

Q.16 What is the effect of the lesion of ‘internal laryngeal nerve’?

Anesthesia of mucous membrane in the supraglottic part of larynx, so the foreign bodies can readily enter larynx.

Q.17 What is the effect of lesion of ‘recurrent laryngeal nerve’?

When bilateral:

• Complete loss of phonation.
• Difficulty in breathing.
  Vocal cords lie in between adduction and abduction.

When unilateral:
Phonation possible because the opposite vocal cord compensates.

Q.18 What is ‘Semon’s law?

In progressive lesions of recurrent laryngeal nerve, abductors of vocal cord are first to be paralyzed and last to recover, as compared to adductors. But in functional paralysis of larynx, adductors are first paralyzed.

Q.19 Why edema of larynx causes suffocation?

Because tissue fluid cannot move downwards due to firm attachment of the mucous membrane to the vocal ligament and thus, causing an obstruction.