10. Functional Anatomy Of The Larynx

Question 1

What are the functions of the larynx?

Answer 1

Airway protection
Ventilation
Cough reflex
Production of sound (phonation)

Question 2

Where does the larynx start and end?

Answer 2

Begins at laryngeal inlet and ends at lower border of cricoid cartilage (C6)

Question 3

What does the larynx lie below?

Answer 3

Hyoid bone

Question 4

What are the cartilages that form the framework of the larynx?

Answer 4

Thyroid cartilage
Cricoid cartilage
Arytenoid cartilages
Epiglottis

Question 5

Which membranes are prt of the framework of the larynx?

Answer 5

Thyrohyoid membrane
Cricotracheal membrane
Cricothyroid membrane

Question 6

What are the Aryepiglottic folds formed from?

Answer 6

Quadrangular membrane

Question 7

What gives shape to the true vocal cord?

Answer 7

Free upper border of cricothyroid membrane

Question 8

What gives shape to false vocal cord?

Answer 8

Free lower border of quadrangular membrane

Question 9

What internally divides the larynx?

Answer 9

Mucosal folds

Question 10

What are the 3 regions of the larynx?

Answer 10

Supraglottis
Glottis
Infraglottis

Question 11

What is the supraglottis?

Answer 11

Laryngeal vestibule - include false cords

Question 12

What type of epithelium lines the larynx except the true vocal cords?

Answer 12

Pseudostratified ciliated columnar epithelium

Question 13

What type of epithelium lines the true vocal cords?

Answer 13

Stratified squamous epithelium

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Question 14

What is the gap between the true vocal cords called?

Answer 14

Rima glottidis

Question 15

When do vocal cords need to be viewed?

Answer 15

Intubation - placement of an endotracheal tube into subglottic region
Flexible nasoendoscopy

Question 16

What is the vallecula?

Answer 16

Recess between tongue and epiglottis where laryngoscope is placed during intubation

Question 17

What do the 2 main actions of the intrinsic laryngeal muscles alter?

Answer 17

Size/shape of laryngeal inlet

Tension/position of vocal cords

Question 18

What are the actions of the intrinsic laryngeal muscles?

Answer 18

Swallowing - close laryngeal inlet and vocal cords, protect respiratory tract
Inspiration and expiration - open vocal cords, allowing movement of air
Phonation and cough reflex - partially closed vocal cords

Question 19

Which intrinsic muscle of the larynx acts to open the vocal cords?

Answer 19

Posterior cricoarytenoid

Question 20

What does the arytenoids position on cricoid determine?

Answer 20

Position of true vocal cords and therefore size of aperture

Question 21

What are the intrinsic muscles innervated by except cricothyroid muscle?

Answer 21

Recurrent laryngeal nerve of vagus (2 - one for each side)

Question 22

What is the cricothyroid muscle innervated by?

Answer 22

External branch of superior laryngeal nerve

Question 23

What is the position of the vocal cords in phonation?

Answer 23

Closely adduct, with small gap for vibrations from expired air forced out

Question 24

What happens in the cough reflex?

Answer 24

Inspire and fill lungs with air
Vocal cords then adducted
Expiration muscles contract
Intrathoracic pressure builds
Then cords suddenly abducted 
Explosive outflow of air

Question 25

Which muscle is involved in controlling tension of vocal cords?

Answer 25

Bilateral contraction of cricothyroid muscles increases tension

Question 26

How does the cricothyroid muscle increase tension in vocal cords?

Answer 26

Tilts thyroid cartilage forward on cricoid, increasing tension in vocal cords Important for reaching higher pitch

Question 27

Why can thyroid surgery sometimes result in hoarseness of voice, especially in high pitched sounds?

Answer 27

Cricoid muscle innervated by external branch of superior laryngeal nerve This nerve is closely related to superior thyroid artery, and can therefore be damaged in thyroid surgery This can result in hoarseness of voice

Question 28

What happens to the larynx during swallowing?

Answer 28

Hyoid bone elevated and moved anteriorly by suprahyoid muscles - larynx moves up and forward Tongue pushes epiglottis posterior lay and aryepiglottic muscles contract Closure of vocal cords

Question 29

What are the branches of the superior laryngeal nerve?

Answer 29

Internal - supraglottic (sensory) | External - cricothyroid (motor)

Question 30

Describe the path of the recurrent laryngeal nerve to the larynx

Answer 30

Arises distally from vagus Passes anteriorly to the loops under right subclavian artery and on left, the arch of aorta Ascends in tracheo-oesophageal groove Close anatomical relationship with thyroid gland and inferior thyroid arteries

Question 31

What can cause injury to recurrent laryngeal nerve?

Answer 31

Thyroid surgery Aortic arch aneurysm Cancer involving apex of lung Disease or surgery involving larynx, oesophagus or thyroid

Question 32

What do unilateral RLN lesions lead to?

Answer 32

Unilateral vocal cord palsies - hoarse voice, ineffective cough

Question 33

What position do paralysed vocal cord assume?

Answer 33

Paramecium position | Between fully abducted and fully adducted

Question 34

What happens in bilateral RLN injuries?

Answer 34

Both vocal cords paralysed and in paramedian position Narrow glottis Significant airway obstruction - emergency surgical airway