Lecture 19- The larynx

Question 1

the pharynx deals wtih a bit of a design flaw…

Answer 1

Air must pass through the nasopharynx and the oropharynx to get to the larynx= shared pathway (air and food)

Question 2

function of the larynx

Answer 2

• Airway protection
  
  • Larynx protects the airway when we eat and drink
• Ventilation
  
  • Conduit for air to pass for breathing
• Cough reflex
  
  • Rapidly expels anything inadvertently entering the airway
• Production of sound (phonation)

Question 3

Anatomy of the larynx

Answer 3

• Larynx sits in front of the pharynx
• Tube supported by cartilaginous tube, ligaments and membrane
• Muscle also help support

Question 4

the larynx is suspended fromt he

Answer 4

hyoid bone

Question 5

where does the larynx begin

Answer 5

• Begins at the laryngeal inlet and ends at the lower border of cricoid cartilage (C6- trachea)
• Continues as the trachea

laryngeal inlet is circles in yellow makrer

Question 6

larynx relationship between the suprahyoid and infrahyoid muscles

Answer 6

Question 7

where does the larynx lie anteriro to

Answer 7

the laryngopharynx

Question 8

posterior view of the larynx

Answer 8

Question 9

• Posterior-laterally to laryngeal inlet the ………. …………is found

Answer 9

piriform fossa

Question 10

• When we eat and drink the position of the epiglottis moves to a more

Answer 10

• horizontal position–> directing food through the piriform fossa and into the oesophagus
  
  • Food can get stuck in the piriform fossa

Question 11

Framework of larynx - Cartilage

Answer 11

• Thyroid (2 lamina – superior and inferior horn)
  
  • When one lamina meets the other lamina = laryngeal prominences – Adams apple
• cricoid cartilage -below thyroid
  
  • inferior horn of thyroid cartilage articulates with the cricoid cartilage- synovial joint
  • thicker at the back than front (signet ring)
• Retinoid cartilage- sits on the cricoid cartilage
• Epiglottis- attached by its stalk to the inner surface of the thyroid cartilage

Question 12

Framework of the larynx: Membranes

Answer 12

Connective tissue sheet- named according to structures they are attached to

Question 13

Surface anatomy : certain cartilages and membranes are palpable

Answer 13

Question 14

laryngeal inlet

Answer 14

• Oval shaped
• Made up of
  
  • Epiglottis
  • Aryepiglottic folds
    
    • Formed by the superior border of the quadrangular membrane
    • Inferior border- false vocal cord

Question 15

Cricothyroid membrane

Answer 15

Free superior margin of the cricothyroid membrane and quadrangular membrane- true vocal cord

Question 16

Larynx is lined with a

Answer 16

mucous membrane

Question 17

• Internal anatomy is shaped by

Answer 17

• folds formed by ligaments/membranes and cartilages
  
  • Quadrangular membrane (inferior boundary)- false vocal cord
  • Superior extension of the cricothyroid membrane- true vocal cord

Question 18

Larynx can be separated into three regions by mucosal folds

Answer 18

• Supraglottic
• Glottis
• Infraglottis

Question 19

Supraglottic

x

Answer 19

• From laryngeal inlet down to the false vocal cords

Question 20

• Glottis

Answer 20

• True vocal cords to about 1cm below here
• Narrowest part of larynx

Question 21

• Infraglottis

Answer 21

Below the glottis

Question 22

betwen the vocal cords (false and true) there is an

Answer 22

• Outpouching of mucous membrane from between the vocal cords–> saccule of larynx
  
  • Between vestibular and vocal folds in small recess (ventricle)–> leads laterally and upwards into saccule (or sinus)à contains mucous glands that keep the true vocal fold moist

Question 23

truve vocal cords are covered in

Answer 23

• Stratified squamous epithelium
  
  • More resistant to damage

Question 24

the larynx with the excpetion of the true vocal cords are lined with

Answer 24

pseudostratified ciliated columnar epithelium

Question 25

laryngoscopic view of larynx e.g. during intubation

Answer 25

Question 26

when will the larynx be visualise

Answer 26

intubation flexible nasoendoscopy

Question 27

intubation

Answer 27

vocal cords mst be views for intubation: placement of an endotracheal tube in subglottic region (i.e. below vocal cords)

Question 28

flexible nasoendoscopy

Answer 28

insert flexible endoscope via nasal cavity and pharynx to then visualise larynx

Question 29

the intrinsic larngeal muscles have 2 main actions

Answer 29

* **to alter** * **Size/shape of laryngeal inlet** * **Tension/position of vocal cords** * Protection- swallowing food * When speaking and coughing and breathing

Question 30

when we swallow what happens to the laryngeal inlet and vocal cords

Answer 30

close laryngeal inlet and vocal cords protecting resp tract

Question 31

during inspiration and expiration what happens to the laryngeal inlet and vocal cords

Answer 31

laryngeal inlet and vocal cords open - allowing movement of air

Question 32

what happens to the vocal cords during phonation

Answer 32

partially adducted - vocal cords come together

Question 33

what happens to the vocal cords during coughing

Answer 33

must go from foricble adduction 9to increase itnrthoarcic pressure) --\> abducted

Question 34

outline how the vocal cords are moved to allow coughing and phonation i.e. adduction/abduction of the vocal cords

Answer 34

* Vocalis muscle run along the length of the vocal cords * muscles associated with arytenoid cartilage causes widening of aperture * responsible for moving outwards and inwards of vocal cords * important one= **posterior cricoarytenoid** (only intrinsic muscle that acts to abduct vocal cords) * all the other intrinsic muscles will act to adduct vocal cords

Question 35

only intrinsic muscle that acts to abduct vocal cords

Answer 35

important one= posterior cricoarytenoid the rest of the intrinsic muscles will act to adduct the vocal cords

Question 37

* intrinsic muscle move cartilage

Answer 37

relative to one another playing a key role in vocal cord movement

Question 39

* arytenoid position on cricoid determines

Answer 39

position of true vocal cords and therefore size of aperture (glottis)

Question 40

all intrinsic muscles are supplied by the ............. ............... ............... excet the ....................

Answer 40

* all muscles supplied by the **recurrent laryngeal nerve of vagus (CN X)** except **cricothyroid muscle**

Question 41

reight/left vocal cord muscles supplies by the

Answer 41

right/left recurrent laryngeal nerve

Question 42

cricothyroid muscle supplies by the

Answer 42

external branch of the superior laryngeal nerve

Question 43

**Cricothyroid muscle** summary

Answer 43

* Intrinsic muscle * Found on the outside of the cartilages * external branch of superior laryngeal nerve * will icnrease tension on vocal cords- importan for reaching higher pitches

Question 44

vocal cord movements: inspiration and expiration

Answer 44

* **Vocal cords aBduct** * **Allows air to pass in and out**

Question 45

**Vocal cord movements:** * **Phonation**

Answer 45

* VC closely aDduct

Question 46

**Vocal cord movements: Cough** (explosion of compressed air)

Answer 46

* insire and fill lungs with air * vocal cords the **aDduct** * expiratory muscles contract * intrathroaric pressure builds * then cords suddenly **abducted** * explisuve outflow of air

Question 47

both vocal cords have to emet in the midline (aDduct) to allow for

Answer 47

phonation and cought

Question 49

if movement of one vocal cord is impaired (e.g. injury to nerve supplying muscles involved in its moveemnt) ....

Answer 49

phonation and cough will be impaired

Question 50

what is this patient doing

Answer 50

B- breathing in

Question 51

**pitch of sound determined by**

Answer 51

**vocal cord tension**

Question 52

* High pitched sounds

Answer 52

Vocal cords taut

Question 53

* Low pitched

Answer 53

Vocal cords less taut

Question 54

what will icnrease the tension of the vocal cords outside the larynx

Answer 54

Bilateral contraction of cricothyroid muscle

Question 55

cricothryoid muscle is innervated by

Answer 55

CNX - vagus external branch of the superior largngeal nerve

Question 56

external branch of the superiro laryngeal supplying the cricothyroid muscle is closely associated to and at risk during

Answer 56

(closely related to superior thryoid artery)--\> can be damaged during thryoid surgery - will cause hoarseness of voice particulalry when attempting higher pitched sounds

Question 58

**Action of cricothyroid muscle**

Answer 58

Tilts thyroid cartilage forward on cricoid increasing tension on vocal cords--\>important for reaching higher pitch

Question 59

* When epiglottis is open

Answer 59

air, food and water can go into the larynx

Question 60

* Epiglottis needs to close during

Answer 60

* swallowing * Directs food to the oesophagus instead of the airway

Question 61

outline what happens to the larynx when we swallow

Answer 61

* Hyoid bone elevated and moves anteriorly by suprahyoid muscles * Larynx moves up and forward * Tongue pushes epiglottis posteriorly and aryepiglottic muscles contract * Narrowing laryngeal inlet * Brining epiglottis from a vertical to a more horizontal position (longitudinal pharyngeal muscles) * Directs food into the piriform fossa into the oesophagus * Closure of vocal cords (glottis)

Question 62

Hyoid bone elevated and moves anteriorly by suprahyoid muscles

Answer 62

helps ensure patency of pharynx so food/fluid can be directed into it

Question 63

vagus nerve innervation to the larynx summary

Answer 63

* Autonomics will also be delivered via CN X to mucosal glands within the larynx

Question 64

superior laryngeal nerve

Answer 64

* a branch of the vagus * gives rise to an internal and external branch * runs very closely to the superior thyroid artery

Question 65

internal branch of the superior laryngeal nerve

Answer 65

purely sensory (supraglottic)

Question 66

external branch of the superior laryngeal nerve

Answer 66

motor to cricothyroid

Question 68

recurrent laryngeal nerve route

Answer 68

* arises distally from the vagus * passes anteriorly to then loops under right SCA (superior cerebellar artery) and on left, arch of the aorta * asends in tracheo-oesophageal groove * close anatomical relationship with thryoid gland and inferior thyroid arteries supplying the gland

Question 69

RLN has a close anatomical relationship with the thyroid gland and inferior thryoid arteries- how does the RLN ascend

Answer 69

in the tracheo-oesophageal groove

Question 70

**Vocal cord palsies**

Answer 70

Injury to recurrent laryngeal nerve

Question 71

example of causes of vocal cord palsies due to injruy to the RLN

Answer 71

1. thyroid sugery- RLN closely related to inferior thyroid artery 2. Aortic arch aneurysm (left RLN) 3. Cancer involving apex of lung (right RLN) (pancoast tumour) 4. Disease or surgery involving larynx, oesophagus or thyroid

Question 72

* Unilateral lesions lead to unilateral vocal cord palsies

Answer 72

* * Hoarse voice * Ineffective cough the paralysed vocal cord assumes a paramedian position - between fully abducted and fully adducted - often the contralateral side will compensate in tiem 9crosses midline to meet vocal cord on affecte dside)

Question 73

* Bilateral lesions of the RLN

Answer 73

* Both vocal cords paralysed and in paramedian position * Narrow glottis * Significant airway obstruction… emergency surgical airway e.g. cricothyroidotomy, tracheostomy

Question 74

Summary of the larynx

Answer 74

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