Larynx

Question 0

Describe the laryngeal skeleton

Answer 0

Single bone/cartilage

1. Hyoid bone
2. Epiglottis:
   - leaf shaped fibrocartilage attached to hyoid and thyroid cartilage
3. Thyroid cartilage:
   - laryngeal prominence (C4) and location of carotid body and common carotid artery bifurcation
   - superior thyroid horns articulate with hyoid
   - inferior thyroid horns articulate with cricoid
4. Cricoid cartilage:
   - signet ring shaped complete cartilage ring (C6)
   - articulates with inferior thyroid and aretynoid cartilage

Paired cartilages

1. Aretynoids:
   - pyramid shaped, involved in vocal cord movement
2. Cuneiform cartilage
3. Corniculate cartilage

Cricovocal ligament/membrane (conus elasticus)

• attaches cricoid cartilage (lower border)
• upper free border to vocal ligament

Question 1

What is the larynx?

Answer 1

Connects the oropharynx to trachea

Functions to…
- protect airway, phonation, cough reflex, respiratory function

Three divisions

• supraglottic: laryngeal inlet to false vocal cords
• glottis: vocal cords and rima glottis
• subglottic: below vocal cords to inferior border of cricoid cartilage

Question 2

What are the laryngeal muscles?

Answer 2

EXTRINSIC: move entire larynx

• suprahyoid (elevators): myelohyoid, geniohyoid, stylohyoid and digastric
• infrahyoid (depressors): sternohyoid, omohyoid, thyrohyoid, sternothyroid

INTRINSIC: act on vocal cords and aryepiglottic folds

• abduction: posterior cricoaretynoid and cricothyroid
• adduction: lateral cricoaretynoid and cricothyroid

Vocal cords have stratified squamous epithelia, plus vocal ligament and vocalist muscle

Question 3

What is the innervation of the larynx?

Answer 3

Vagus nerve to superior laryngeal nerve

• sensory above true vocal cords (internal laryngeal)
• motor above true vocal cords: cricothyroid (external laryngeal)

Vagus nerve to recurrent laryngeal nerve

• sensory below true vocal cords
• motor to all intrinsic muscles
• palsy can result in hoarseness of voice (red flag if > 3/52)
• recurrent laryngeal nerve loops down below aortic arch and rises back up so can be affected by tumours within the chest and neck

Question 4

What is the blood supply of the larynx?

Answer 4

External carotid artery to superior thyroid artery and then superior laryngeal artery
- drained by superior laryngeal vein to superior thyroid vein and to IJV

Subclavian artery to inferior thyroid artery and then inferior laryngeal artery
- drained by inferior laryngeal vein to inferior thyroid vein and to IJV