The larynx Flashcards

1
Q

What is the larynx?

A

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

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2
Q

What are the functions of the larynx?

A
  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
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3
Q

What are the key structures in the laryngeal skeleton?

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

What is the epiglottis?

A

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

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4
Q

How is the epiglottis connected to the thyroid cartilage?

A

By the thyroepiglottic ligament

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4
Q

How are the hyoid bone and thyroid cartilage connected?

A

by the thyrohyoid membrane and thyrohyoid muscle

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5
Q

What are the features of the thyroid cartilage?

A
  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
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6
Q

What are the features of the cricoid?

A
  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
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7
Q

Where are the arytenoids?

A

on top of the cricoid

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8
Q

What are the cricoarytenoid joints?

A

synovial joints between the arytenoids and the cricoid lamina

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9
Q

Where do the vocal folds attach?

A
  1. anteriorly to thyroid cartilage
  2. posteriorly to the vocal processes of the arytenoids
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10
Q

What movements are possible at each cricoarytenoid joint?

A
  1. sliding apart/together
  2. rotation about a vertical axis
  3. tilting forwards or backwards
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11
Q

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

A
  1. slide medially = adduction (close) of vocal cords
  2. slide laterally = abduction (open) of vocal folds
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12
Q

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

A
  1. rotate inwards = adduction (close) of vocal folds
  2. rotation outwards = abduction (open) of vocal folds
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13
Q

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

A
  1. tilting backwards = inc length and tension, dec thickness
  2. tilting forwards = dec length and tension, inc thickness
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14
Q

What is the action of the cricothyroid muscle?

A
  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
15
Q

What innervates the cricothyroid muscle?

A

superior laryngeal nerve - branch of CNX vagus

16
Q

Where is the posterior cricoarytenoid muscle?

A

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

17
Q

What is the action of the posterior cricoarytenoid muscle?

A

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

18
Q

Where are the lateral cricoaryntenoid muscles?

A

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

19
Q

What is the action of the lateral cricoarytenoid muscles?

A

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

20
Q

Where are the interarytenoid muscles?

A

Extend between the arytenoids both laterally and oblique

21
Q

What is the action of the interarytenoid muscles?

A

adduct the vocal folds

22
Q

What is the thyroarytenoid muscle?

A

a broad muscle running from teh arytenoid to the thyroid cartilage

23
Q

What is the action of the thyroarytenoid muscle?

A

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

24
Q

What is the vocalis muscle?

A

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

25
Q

What are the vestibular folds?

A
  1. ‘false vocal cords’
  2. superior to vocal folds
  3. respiratory epithelium (different mucosa to vocal folds)
  4. no role in phonation
26
Q

What are the mucosas of the larynx?

A
  1. larynx = lined with respiratory epithelium
  2. vocal folds = lined with stratified squamous epithelium
27
Q

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

A
  1. superior laryngeal nerve
  2. recurrent laryngeal nerve
28
Q

What does the superior laryngeal nerve innervate?

A
  1. sensory to mucosa of larynx
  2. motor to cricothyroid muscles
29
Q

What does the recurrent laryngeal nerve innervate?

A

motor to all laryngeal muscles except cricothyroid

30
Q

What results from damage to superior laryngeal nerve?

A
  1. loss of sensation to larynx = no cough reflex/swallow initiation -> aspiration
  2. loss of motor to cricothyroid muscle - difficulty regulating pitch
31
Q

What results from damage to recurrent laryngeal nerve?

A
  1. all muscles affected on paralysed side except cricothyroid and interarytenoids
  2. because the interarytenoids still work - partially adducted so harsh raspy voice
32
Q

What can cause damage to recurrent laryngeal nerve?

A

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