The larynx

Question 1

What is the larynx?

Answer 1

Part of the respiratory tract which is reinforced with cartilages which articulate with each other at synovial joints and can be moved with precision

Question 2

What are the functions of the larynx?

Answer 2

1. protection of the lower respiratory tract to prevent inhalation of food or liquids during swallowing or vomiting
2. phonation by vibration of vocal folds

Question 3

What are the key structures in the laryngeal skeleton?

Answer 3

1. hyoid bone
2. thyroid cartilage
3. cricoid cartilage
4. arytenoid cartilages
5. epiglottis

Question 4

What is the epiglottis?

Answer 4

Cartilage which moves over the opening of the larynx to protect the airway

Question 4

How is the epiglottis connected to the thyroid cartilage?

Answer 4

By the thyroepiglottic ligament

Question 4

How are the hyoid bone and thyroid cartilage connected?

Answer 4

by the thyrohyoid membrane and thyrohyoid muscle

Question 5

What are the features of the thyroid cartilage?

Answer 5

1. large lamina on both sides
2. laryngeal prominence
3. open posteriorly
4. 2 superior horns (each side) which connect to hyoid by thyrohyoid membrane
5. 2 inferior horns (each side) connect to cricoid

Question 6

What are the features of the cricoid?

Answer 6

1. signet in shape
2. only complete ring of cartilage in respiratory system
3. attached to thyroid by cricothyroid joint
4. articulates with cricoid cartilage

Question 7

Where are the arytenoids?

Answer 7

on top of the cricoid

Question 8

What are the cricoarytenoid joints?

Answer 8

synovial joints between the arytenoids and the cricoid lamina

Question 9

Where do the vocal folds attach?

Answer 9

1. anteriorly to thyroid cartilage
2. posteriorly to the vocal processes of the arytenoids

Question 10

What movements are possible at each cricoarytenoid joint?

Answer 10

1. sliding apart/together
2. rotation about a vertical axis
3. tilting forwards or backwards

Question 11

What are the effects of the sliding motion of the arytenoids?

Answer 11

1. slide medially = adduction (close) of vocal cords
2. slide laterally = abduction (open) of vocal folds

Question 12

What are the effects of the rotation movement of the arytenoids?

Answer 12

1. rotate inwards = adduction (close) of vocal folds
2. rotation outwards = abduction (open) of vocal folds

Question 13

What are the effects of the tilting movement of the arytenoids?

Answer 13

1. tilting backwards = inc length and tension, dec thickness
2. tilting forwards = dec length and tension, inc thickness

Question 14

What is the action of the cricothyroid muscle?

Answer 14

1. pulls thyroid cartilage forward and down
2. move cricoid carilage up (so arytenoids move back)
3. stretch vocal cords, making them thinner, and increasing pitch

Question 15

What innervates the cricothyroid muscle?

Answer 15

superior laryngeal nerve - branch of CNX vagus

Question 16

Where is the posterior cricoarytenoid muscle?

Answer 16

extends from the muscular process of the arytenoid to the posterior lamina of the cricoid cartilage

Question 17

What is the action of the posterior cricoarytenoid muscle?

Answer 17

rotates the arytenoids outwards to abduct the vocal folds and open the rima glottis - these are the only abductors of the vocal folds

Question 18

Where are the lateral cricoaryntenoid muscles?

Answer 18

extend between muscular process of arytenoid to superior/anterior areas of the cricoid

Question 19

What is the action of the lateral cricoarytenoid muscles?

Answer 19

rotates the arytenoids inwards to adduct the vocal folds and close the rima glottis

Question 20

Where are the interarytenoid muscles?

Answer 20

Extend between the arytenoids both laterally and oblique

Question 21

What is the action of the interarytenoid muscles?

Answer 21

adduct the vocal folds

Question 22

What is the thyroarytenoid muscle?

Answer 22

a broad muscle running from teh arytenoid to the thyroid cartilage

Question 23

What is the action of the thyroarytenoid muscle?

Answer 23

pulls the arytenoids closer to the thyroid cartilage, making the vocal folds slacker/thicker/looser for lower pitch, making broad adjustments

Question 24

What is the vocalis muscle?

Answer 24

the inner portion of the thyroarytenoid muscle which makes finer adjustments to the thickness of the vocal folds/pitch

Question 25

What are the vestibular folds?

Answer 25

1. 'false vocal cords' 2. superior to vocal folds 3. respiratory epithelium (different mucosa to vocal folds) 4. no role in phonation

Question 26

What are the mucosas of the larynx?

Answer 26

1. larynx = lined with respiratory epithelium 2. vocal folds = lined with stratified squamous epithelium

Question 27

What are the branches of the vagus nerve used in the larynx?

Answer 27

1. superior laryngeal nerve 2. recurrent laryngeal nerve

Question 28

What does the superior laryngeal nerve innervate?

Answer 28

1. sensory to mucosa of larynx 2. motor to cricothyroid muscles

Question 29

What does the recurrent laryngeal nerve innervate?

Answer 29

motor to all laryngeal muscles except cricothyroid

Question 30

What results from damage to superior laryngeal nerve?

Answer 30

1. loss of sensation to larynx = no cough reflex/swallow initiation -> aspiration 2. loss of motor to cricothyroid muscle - difficulty regulating pitch

Question 31

What results from damage to recurrent laryngeal nerve?

Answer 31

1. all muscles affected on paralysed side except cricothyroid and interarytenoids 1. because the interarytenoids still work - partially adducted so harsh raspy voice

Question 32

What can cause damage to recurrent laryngeal nerve?

Answer 32

usually unilateral damage from lung pathology (usually left) or thyroid gland operations