Anatomy

Question 1

What are the components of the larynx?

Answer 1

The supraglottis, glottis (contains vocal chords and 1cm below this and subglottis.

Question 2

What is the blood supply to the larynx?

Answer 2

The superior and inferior laryngeal artery (follows recurrent laryngeal nerve into larynx).

Question 3

What is the innervation of the larynx?

Answer 3

The branches of the vagus nerve:

1. Recurrent laryngeal nerve

• provides sensory innervation to the infraglottis, and motor innervation to all the internal muscles of larynx (except the cricothyroid).

2. Superior laryngeal nerve

– the internal branch provides sensory innervation to the supraglottis, and the external branch provides motor innervation to the cricothyroid muscle.

Question 4

What can cause recurrent laryngeal nerve palsy? What is the result of this?

Answer 4

This will result in unilateral vocal chord paralysis, the other side will tend to compensate for this but will still have a hoarse voice. If its bilateral will cause breathing issues.

Apical lung tumour
Thyroid cancer
Aortic aneurysm
Cervical lymphadenopathy
Iatrogenic (particularly during thyroid surgery due to the close relationship with the inferior thyroid artery).

Question 5

What happens in partial vocal chord paralysis?

Answer 5

The vocal chord becomes paralysed in the adducted position, if this is bilateral its an emergency airway obstruction - emergency surgical intervention required.

Question 6

Describe the muscles of the larynx?

Answer 6

Muscles of the larynx can be divided into external which lift up, and depress the larynx for swallowing and internal muscles which act on the individual muscles within the larynx for breathing and phonation.

Question 7

What are the external muscles of the larynx? What is their action?

Answer 7

The suprahyoid muscles and the stylopharyngeus elevate the larynx,

whilst the infrahyoid muscles depress the larynx.

Question 8

What are the internal muscles of the larynx? What is their innervation and action?

Answer 8

1. CRICOTHYROID: Stretches and tenses the vocal ligament. Forceful speech - “singers muscle”.
   Innervation: External laryngeal nerve (branch of superior laryngeal).

All others innervated by inferior laryngeal nerve (branch recurrent laryngeal)

2. THYROARYTENOID: relaxes vocal ligament “soft voice”
3. POST CRICOARYTENOID: sole abductors of vocal folds
4. LATERAL CRICOARYTENOID: adduction vocal folds
5. TRANSVERSE AND OBLIQUE ARYTENOIDS: adduction arytenoid cartilage, narrows laryngeal inlet