The Larynx 2

Question 1

What is the vocalis?

Answer 1

This is a deep triangular bundle of fibres of the thyroarytenoid complex that lies close to the vocal ligament.

Question 2

What can the vocalis do?

Answer 2

The fibres of the vocalis can selectively separate one part of the vocal ligament while the rest remains adducted.

Question 3

Which muscle fibres are responsible for producing sounds of the highest pitch?

Answer 3

The vocalis muscle fibres do this when the vocal ligaments are already maximally tensed by the cricothyroid muscle.

Question 4

Which muscles do the cricothyroid muscles oppose the pull of?

Answer 4

They oppose the pull of the posterior cricoarytenoid muscles on the arytenoid cartilages. They also oppose the pull of the thyroarytenoids.

Question 5

What will the thyroarytenoids do?

Answer 5

They shorten the span between the thyroid cartilage and the arytenoids.

Question 6

Where do the cricothyroid muscles lie?

Answer 6

They lie on the outer surface of the larynx.

Question 7

What is the function of the cricothyroid muscle?

Answer 7

They produce tension in the vocal ligaments. They are especially involved in producing high voice tones.

Question 8

How do cricothyroid muscles act?

Answer 8

They act by tilting the cricoid cartilage relative to the thyroid at the cricothyroid joints (and vice versa).

Question 9

How do the posterior cricothyroids assist in the tensing action of the cricothyroids?

Answer 9

By pulling back on the arytenoids.

Question 10

What is the interior of the larynx lined with?

Answer 10

It is lined with mucous membranes.

Question 11

From the tongue, what is the mucous membrane reflected onto?

Answer 11

It is reflected onto the epiglottis from the tongue.

Question 12

In the region where the mucous membrane is reflected, what happens to the mucous membrane?

Answer 12

It is thrown into folds

• 1 median glossoepiglottic fold
• 2 lateral glossoepiglottic folds.

Question 13

What is the depression of each side of the median fold called?

Answer 13

It is called the vallecula.

Question 14

What does the mucous membrane form between the inner and outer walls of the larynx?

Answer 14

It forms a piriform recess/ fossa on each side.

Question 15

How is the plane of the inlet of the larynx orientated?

Answer 15

It is almost vertical.

Question 16

What does the inlet of the larynx lead into?

Answer 16

It leads into the upper part of the larynx = vestible.

Question 17

What does the vestibule of the larynx extend from, to?

Answer 17

Extends from the inlet of the larynx down to the vestibular ligaments.

Question 18

What is the gap between the 2 vestibular folds called?

Answer 18

This is called the rima vestibuli.

Question 19

Between the vestibular folds and the vocal folds what is there?

Answer 19

There is an opening that leads into the ventricle of the larynx.

Question 20

What is the most anterior part of the opening between the vestibular folds and the vocal folds called?

Answer 20

This is called the saccule of the larynx.

Question 21

Where do the ventricle and saccule extend up to?

Answer 21

They extend upwards on the outer side of the quadrangular membrane.

Question 22

Where does the nerve supply for the larynx come from?

Answer 22

It comes from the vagus nerve through its superior and recurrent laryngeal branches.

Question 23

Where does the superior laryngeal nerve leave the vagus?

Answer 23

It leaves the vagus high in the neck.

Question 24

After passing deep to the carotids what happens to the superior laryngeal nerve?

Answer 24

It divides into internal and external branches.

Question 25

How does the internal laryngeal nerve enter the larynx?

Answer 25

By piercing the thyrohyoid membrane.

Question 26

What does the internal laryngeal nerve supply sensation to?

Answer 26

It supplies sensation to the mucous membrane of the larynx above the vocal cords, which includes the piriform fossa.

Question 27

What else does the internal laryngeal nerve supply?

Answer 27

• both surfaces of the epiglottis
• aryepiglottic fold
• vallecula

Question 28

What does the external laryneal branch of the superior laryngeal nerve supply?

Answer 28

It supplies the cricothyroid muscle.

Question 29

Where is the cricothyroid muscle in relation to the larynx?

Answer 29

It is outside the larynx.

Question 30

In its course to the cricothyroid muscle, what is the external laryngeal nerve closely associated with?

Answer 30

It is closely associated with the superior thyroid artery therefore it must be protected when ligating the superior thyroid artery during operations on the thyroid gland.

Question 31

How does the recurrent laryngeal nerve enter the larynx?

Answer 31

It enters the larynx behind the cricothyroid joint.

Question 32

What does the recurrent laryngeal nerve supply?

Answer 32

• It supplies the intrinsic muscles of the larynx except for the cricothyroid.
• supplies sensation to mucous membranes below the vocal folds.

Question 33

What do the terminal branches of the recurrent laryngeal nerve mingle with?

Answer 33

They mingle with branches of the superior laryngeal nerve.

Question 34

What is the cricopharyngeal part of the inferior constrictor of the pharynx supplied by?

Answer 34

It is supplied by twigs from either the recurrent laryngeal nerve of the external laryngeal nerve.

Question 35

On its way to the larynx, what is the recurrent laryngeal nerve closely associated with?

Answer 35

It associated with the inferior thyroid artery. Therefore damage to the recurrent laryngeal nerve is a hazard during thyroidectomy.

Question 36

When is lymphatic drainage of the larynx important?

Answer 36

It is important in malignant disease.

Lymphatics carry tumour cells first to local lymph nodes in the neck and eventually from here they spread widely throughout the body.

Question 37

What do the lymphatics of the larynx form?

Answer 37

They form 2 distinct systems – one above and one below the vocal cords.

Question 38

Where do anastomoses of the 2 distinct divisions of the larynx lymphatics occur?

Answer 38

They occur in the posterior wall of the larynx.

Question 39

Where do lympathics from the upper group reach?

Answer 39

They reach the upper deep cervical nodes.

Question 40

What do the lymphatics from the upper group pierce?

Answer 40

They pierce the thyrohyoid membrane.

Question 41

After the lymphatics pierce the thyrohyoid membrane, what vessels do they follow?

Answer 41

They follow the superior laryngeal vessels.

Question 42

What do the lower vessels pierce?

Answer 42

They pierce the cricovocal membrane.

Question 43

Where do the lower lymph vessels drain into?

Answer 43

• pretracheal nodes on the cricovocal membrane
• paratracheal nodes along the course of the recurrent laryngeal nerve

Question 44

What does the most common obstruction to the airway result from?

Answer 44

It results from food or other objects becoming lodged in the laryngeal inlet. This + spasm of the laryngeal muscles will occlude the airway.

Question 45

How can we dislodge an obstruction in the airway?

Answer 45

By coughing or by a finger removing the bolus or by sharply compressing the subject’s chest from behind with tightly interlocked arms.

Question 46

What happens if we fail to achieve a clear airway using simple methods?

Answer 46

This is serious and in an emergency situation, an incision is made through the cricothyroid membrane in the midline.

Question 47

Where does the cricothyroid membrane lie?

Answer 47

It lies below the level of the vocal folds and at the entrance of the trachea.

Question 48

What kind of items get stuck in the piriform fossa?

Answer 48

Awkward items that are swallowed with difficulty and sometimes need to be removed.

Question 49

Why do anaesthetists recognise the importance of identifying the valleculae at the base of the tongue?

Answer 49

This is really important when intubating patients.

The tip of a laryngoscope is placed on the vallecula and the base of tongue is drawn forwards to bring the laryngeal inlet into view. Once we can see the laryngeal inlet, we can pass the tube through the rima glottidis and into the trachea.

Question 50

What can happen if there is an injury to one recurrent laryngeal nerve?

Answer 50

This could result in the affected cord being fixed in either an abducted or adducted position.

Question 51

What will happen if the vocal cord is fixed in the adducted position? (what will the subject complain off)

Answer 51

The subject will complain of breathlessness (dyspnoea) on exertion.

Question 52

What will the patient complain off if the cord is abducted?

Answer 52

The complaint will be more of hoarseness and weakness of the voice with little or no breathlessness.

Question 53

What happens when there is bilateral paralysis of the recurrent laryngeal nerves?

Answer 53

There will be adducted cords. This results in dyspnoea and hoarseness.

Question 54

What happens when there is damage to the external laryngeal nerve?

Answer 54

This results in the paralysis of the crciothyroid muscle.

The voice is hoarse because the vocal folds are flabby and rubber band like.

There is difficulty singing high notes and the voice tires quickly.

Recovery occurs when the opposite cord and muscle adapt.