Lecture 16-Larynx

Question 1

From which bone is the larynx suspended?

Answer 1

Hyoid bone

Question 2

True or false: the larynx is part of the respiratory system as it continues as the trachea at C5 (lower border of cricoid cartilage)

Answer 2

FALSE - C6, not C5

Question 3

What is the main function of the larynx?

Answer 3

Protective sphincter for lower resp tract so no food enters

Question 4

What are the three single cartilages making up the larynx?

Answer 4

Thyroid, cricoid and epiglottis

Question 5

Which paired cartilage of the larynx do we need to know?

Answer 5

Arytenoid cartilage

Question 6

What gives the larynx its shape?

Answer 6

Membranes and ligaments connecting cartilages together

Question 7

What are the four membranes of the larynx?

Answer 7

Thyrohyoid membrane, cricotracheal membrane, cricothyroid membrane and quadrangular membrane

Question 8

Which cartilage is the only complete ring of cartilage in the respiratory tract?

Answer 8

Cricoid cartilage

Question 9

Where is the epiglottis attached to?

Answer 9

Inner surface of thyroid cartilage

Question 10

When is a cricothyroidotomy used?

Answer 10

When the patient can’t be intubated or ventilated, to allow them to breathe

Question 11

What does the quadrangular membrane join?

Answer 11

Edges of epiglottis to arytenoid membrane and inner surface of thyroid cartilage

Question 12

What forms the margins of the oval inlet of the larynx?

Answer 12

Aryepiglottic folds

Question 13

What are the two types of vocal cord?

Answer 13

• False vocal cord: vestibular ligament = lower border of quadrangular membrane
• True vocal cord: vocal ligament = thickened edge of upper border of cricothyroid ligament

Question 14

What do internal mucosal folds divide the larynx into?

Answer 14

Supraglottis, glottis and infraglottis

Question 15

What keeps the vocal cords moist (ew)?

Answer 15

Between the vestibular and vocal folds is a small recess which leads into a saccule/sinus that contains mucous glands that keep the vocal cords moist

Question 16

What type of epithelium lines the larynx?

Answer 16

Psuedostratified ciliated columnar epithelium

Question 17

What type of epithelium lines the true vocal cords?

Answer 17

Stratified squamous epithelium

Question 18

What are the two main actions of the laryngeal muscles?

Answer 18

• Alter the size and shape of the inlet

- move position/alter tension in vocal cords

Question 19

True or false: laryngeal muscles open the larynx to allow air to move during inspiration and expiration

Answer 19

TRUE

Question 20

Which is the only muscle that abducts the vocal cords?

Answer 20

Posterior cricoarytenoid

Question 21

What determines the position of the true vocal cords and therefore the size of the aperture?

Answer 21

Position of arytenoids on cricoid cartilage

Question 22

What do the intrinsic muscles of the larynx do?

Answer 22

Move the vocal cords

Question 23

Which nerve innervates the intrinsic muscles of the larynx and what is the exception?

Answer 23

• Recurrent laryngeal nerve of CN X

- Cricothyroid supplied by external branch of superior laryngeal nerve of CN X

Question 24

Describe the position of the vocal cords during inspiration and expiration

Answer 24

Abducted to allow air flow

Question 25

Describe the position of the vocal cords during phonation

Answer 25

Adducted to vibrate air -> pitch

Question 26

Describe the position of the vocal cords during the cough reflex

Answer 26

Powerfully adducted and after intrathoracic pressure builds up, cords suddenly abducted

Question 27

What determines the pitch of sound?

Answer 27

Tension of vocal cords

Question 28

Describe how the vocal cords produce a high-pitched sound

Answer 28

Held taut

Question 29

Describe how the vocal cords produce a low-pitched sound

Answer 29

Relaxed cords

Question 30

Contraction of which muscle increases the length and tension in the vocal cords?

Answer 30

Cricothyroid muscle

Question 31

True or false: cricothyroid is on the outside of the larynx, despite being an intrinsic muscle

Answer 31

TRUE (only intrinsic muscle to do this)

Question 32

What can injury to the superior laryngeal nerve lead to?

Answer 32

Hoarse voice, especially when attempting high-pitched sound

Question 33

True or false: superior laryngeal nerve is closely related to the superior thyroid artery so during surgery, it is easy to damage the nerve

Answer 33

TRUE

Question 34

What is the function of the internal branch of the superior laryngeal nerve?

Answer 34

Sensory to above the vocal cords

Question 35

Describe the course of the recurrent laryngeal nerve

Answer 35

Loops under arch of aorta on left and right subclavian artery on right and ascends in tracheo-oesophageal groove

Question 36

Which nerve provides sensory innervation below the vocal cords?

Answer 36

Recurrent laryngeal nerve

Question 37

What is the difference between unilateral and bilateral recurrent laryngeal nerve injury in terms of breathing?

Answer 37

• Unilateral doesn’t impede breathing because the rema glottidis (aperture) is big enough for air
• Bilateral leads to significant airway obstruction -> stridor, hypoxia, cyanosis and need surgery/cricothyroidotomy

Question 38

Carcinomas of which region of the larynx can lead to metastases?

Answer 38

Supra and infraglottic regions because they drain to neck and paratracheal nodes

Question 39

What is croup?

Answer 39

Inflammation of upper resp tract due to viral infection eg adenovirus, measles

Question 40

What are the symptoms of croup?

Answer 40

Harsh barking cough, stridor, hoarse voice

Question 41

What is epiglottitis?

Answer 41

Strep, staph or herpes infection leading to sore throat, fever and painful swallowing