Anatomy of the larynx

Question 1

Identify the neck fascial compartments in the image.

Answer 1

Purple: pretracheal.

Green: investing

Orange: prevertebral

Red: carotid sheaths x2

Question 2

Identify the labelled structures

Answer 2

Left: strap muscles

Right from top- mandible, hyoid bone, left clavicle, manubrium

Question 3

Where are the strap muscles located and what can they function as?

Answer 3

Pretracheal fascia, accessory muscles of inspiration during forced breathing

Question 4

What vertebral level is the larynx found at?

Answer 4

C4-C6

Question 5

Which structures are found within the carotid sheath?

Answer 5

Internal jugular vein, internal and common carotid arteries, deep cervical lymph nodes, vagus nerve

Question 6

What are the vertebral levels of:

a) the hyoid bone
b) the upper border of the thyroid cartilage
c) the cricoid cartilage

Answer 6

a) C3
b) C4
c) C6

Question 7

What happens at the level of the C6 vertebra?

Answer 7

Larynx becomes trachea; pharynx becomes oesophagus

Question 8

What are the functions of the larynx?

Answer 8

Cartilages help maintain URT patency; vocal cords produce sound; helps to prevent foreign body entrance into the LRT

Question 9

What are the “skeletal” components of the larynx?

Answer 9

The epiglottis; the thyroid cartilage; the cricoid cartilage; artyenoid cartilage; corniculate and cuneiform cartilages.

Question 10

What is different about the epiglottis compared to the rest of the skeletal components of the larynx?

Answer 10

Composed of elastic cartilage rather than hyaline

Question 11

Identify the labelled structures

Answer 11

Clockwise from top:

Laryngeal prominence

Inner aspect of thyroid cartilage

Vocal process of artyenoid cartilage

Muscular process of artyenoid cartilage

Right and left artyenoid cartilages

Cricoid cartilage

Rima glottidis

Right vocal cord

Question 12

Where do the vocal cords attach?

Answer 12

Inner aspect of thyroid cartilage and vocal process of artyenoid cartilage

Question 13

In what situation would cricoid pressure be applied? Why does this only work at this particular area?

Answer 13

In emergency anaethesia- prevents regurgitation/aspiration but maintains patency. Only works here because this is the only point the larynx is a complete ring

Question 14

When intubating why is it important to avoid placing the tube in a main bronchus?

Answer 14

Will only inflate ipsilateral lung; contralateral lung will collapse

Question 15

What is the space betwen the posterior tongue and the epiglottis called?

Answer 15

Vallecula

Question 16

What kind of mucosa is found in the larynx, and what is the exception to this? Why is this the case?

Answer 16

Respiratory with the exception of vocal folds, which is stratified squamous- protective

Question 17

What are the characteristic features of respiratory mucosa?

Answer 17

Mucus production and cilia

Question 18

How does the general sensory nerve supply to the larynx differ posterior to the vocal cords, compared to inferior?

Answer 18

Posterior: supplied by superior laryngeal branches of the vagus nerve. Vocal cords and inferior to the vocal cords- recurrent laryngeal branch of the vagus nerve.

Question 19

What is the motor supply to the larynx?

Answer 19

Branches of the vagus nerve

Question 20

How do the intrinsic muscles of the larynx work to move the vocal cords?

Answer 20

Attach to cartilage which in turn move the vocal cords

Question 21

What are the four categories of intrinsic muscle of the larynx?

Answer 21

Tensors, relaxers, abductors, adductors

Question 22

What are the four stages in voice production?

Answer 22

1. Inspiration using the diaphragm (phrenic nerve) and intercostals
2. Controlled expiration
3. Phonation in the vocal cords
4. Articulation in the mouth (tongue and lips) and the nasal cavity

Question 23

How is the function of the vagus nerve in the palate, pharynx and larynx tested?

Answer 23

1. Swallowing water- does the larynx move up? Do they splutter (suggests abnormal swallow and abnormal cough)
2. Listen to the patient speak- hoarseness may indicate dysfunction of the intrinsic muscles of the larynx
3. Ask to cough- is the cough powerful (also requires functioning nerve supply to diaphragm, abdominals etc)