Larynx & Pharynx

Question 1

True or false? The thyroid cartilage is closed over posteriorly.

Answer 1

False. It is deficient posteriorly.

Question 2

What are the two movements of the arytenoid cartilages?

Answer 2

Swivelling & sliding.

Question 3

How do we produce sound using the vocal ligaments?

Answer 3

We adduct them and push air up through them, causing them to vibrate against each other.

Question 4

Name the borders of the quadrangular membrane.

Answer 4

Anterior: aryepiglottic ligament
Medial: epiglottis
Posterior: vestibular ligament
Lateral: arytenoid cartilage

Question 5

What does contraction of the posterior cricoarytenoid muscles do?

Answer 5

It adducts the muscles, which pull the arytenoid processes and abducts the vocal cords.

Question 6

What does contraction of the lateral cricoarytenoid muscles do?

Answer 6

It abducts the muscles, which pull the arytenoid processes and adducts the vocal cords.

Question 7

Which muscles are responsible for the swivel movement of the arytenoids?

Answer 7

The posterior & lateral cricothyroid muscles.

Question 8

Which muscles are responsible for the sliding movement of the arytenoids?

Answer 8

The transverse & oblique arytenoid muscles.

Question 9

What happens when vocalis & thyroarytenoid contract?

Answer 9

They pull the angle of the thyroid cartilage back toward the arytenoids, causing the vocal ligaments to become more lax and vibrate with a lower frequency, producing a lower pitch sound.

Question 10

What happens when cricothyroid contracts?

Answer 10

The vocal cords are tightened and produce a higher pitch sound.

Question 11

Describe which muscles are used to produce higher/lower pitch sounds.

Answer 11

To produce lower pitch sounds, vocalis and thyroarytenoid contract, making the vocal ligaments become more lax and vibrate with a lower frequency.

For high pitch sounds, cricothyroid contracts and the vocal ligaments are tightened.

Question 12

Which structures does the internal laryngeal nerve supply?

Answer 12

It provides sensory innervation to the mucosa ABOVE the vocal folds.

Question 13

Which structures does the external laryngeal nerve supply?

Answer 13

The cricothyroid muscle.

Question 14

What will happen if the external laryngeal nerve is damaged?

Answer 14

You won’t be able to regulate pitch and produce higher sounds.

Question 15

Which structures does the recurrent laryngeal nerve supply?

Answer 15

The intrinsic muscles (except cricothyroid) and the mucosa BELOW the vocal ligaments.

Question 16

What will happen if the recurrent laryngeal nerve is damaged on one side?

Answer 16

The vocal ligament on that side will fall into a position halfway between abduction & adduction and won’t be able to move. When you try to push air between them, you’re not going to get good vibration, so you get a hoarse voice and stridor (a sense of effort in speaking).

Question 17

What are the main vessels supplying the larynx?

Answer 17

The superior thyroid & superior laryngeal vessels.

Question 18

If you needed to do an emergency airway puncture, would you use a tracheotomy or a cricothyroid membrane puncture? Why?

Answer 18

You only do tracheotomies in clinical settings because of how vascular the area is - you would definitely cut a vessel, letting blood drain into the airways and essentially drowning your patient. In an emergency, you should look for the cricothyroid membrane.

Question 19

What are the two functions of salpingopharyngeus?

Answer 19

Elevating the pharynx/pulling on the opening of the auditory tube.

Question 20

What are the two functions of palatopharyngeus?

Answer 20

Elevating the pharynx/depressing the soft palate.

Question 21

What is the function of stylopharyngeus?

Answer 21

Elevating the pharynx.

Question 22

From where does the pharynx receive its sensory nerve supply?

Answer 22

The trigeminal nerve (pharyngeal branches of maxillary division), the glossopharyngeal nerve (pharyngeal branches) and the vagus nerve (internal laryngeal nerve).

Question 23

From where does the pharynx receive its motor nerve supply?

Answer 23

The pharyngeal branches of vagus, except for stylopharyngeus, which is innervated by the glossopharyngeal nerve.

Question 24

What is the role of the soft palate?

Answer 24

It seals the nasal cavity during swallowing and coughing, and also seals the oral cavity during chewing to allow unimpeded breathing.

Question 25

What is the function of tensor & levator veli palatini?

Answer 25

They contribute to releasing pressure from the middle ear and can also lift the soft palate.

Question 26

From where do the muscles supporting the soft palate receive their innervation?

Answer 26

The pharyngeal branches of vagus, except for tensor veli palatini, which is innervated by the trigeminal nerve.

Question 27

What is the function of palatoglossus & palatopharyngeus?

Answer 27

They depress the soft palate, pulling the uvula down.

Question 28

Describe the process of swallowing and the muscles involved at each step.

Answer 28

1. Food is broken down by the mastication muscles, forming a bolus. The back of the tongue is elevated (palatoglossus) and the soft palate is pulled against it to keep food in the oral cavity.
2. The bolus is moved to the back of the mouth via a rolling motion of the tongue.
3. Tensor & levator veli palatini elevate the soft palate and close off the nasal cavity to prevent the bolus from entering.
4. The larynx & pharynx are elevated (salpingopharyngeus & palatopharyngeus) to bring the bolus close to the oesophagus.
5. The laryngeal inlet is closed to prevent the bolus from entering the trachea.
6. The bolus is pushed down the oropharynx and over the epiglottis.
7. The bolus is forced down the laryngopharynx and into the oesophagus (through joint activity of constrictors & cricopharyngeus creating a peristaltic wave motion).
8. The larynx is depressed to return to normal position, mainly by elastic recoil.