Session 11- the larynx Flashcards Preview

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Flashcards in Session 11- the larynx Deck (67):
1

What are the roles of the larynx?

  • Portecting the airway 
  • Phonation 
  • Breathing 
  • Swallowing 

2

Describe the 2 surfaces of the epiglottis

  • On top:
    • Stratified squamous as in contact with the bolus so same covering as inside of the mouth 
  • Bottom:
    • Pseudostratified columnar as in contact with the airway 

3

What is the epiglottis made up of? What does it do?

  • Fibrocartilage 
  • Acts as a safety flap over the larynx 

4

What is the epiglottis attached to?

  • Posteriorly to the thyroid cartilage by the thyroepiglottic ligament 

5

What is the vallecula?

  • Depression between the tongue base and the epiglottis 

6

Describe the general things that happen when swallowing

  • Epiglottis is pulled down to cover the larynx 
  • The larynx and thyroid cartilage are pulled up 
  • The food bolus is directed lateral to the epiglottis into the piriform fossae (these become continuous with the oesophagus)
  • Further contraction causes swallowing 

7

Where can foreing objects become lodged when swallowing?

In the piriform fossae 

8

What can cause epiglottitis? What does it present as?

  • Haemophilus influenze 
  • Can present as sore throat, fever, drooling and sound when breathing in 

9

Describe the shape of the epiglottis 

More U shaped in children than in adults 

10

Name the cartilages

  • Epiglottis 
  • Thyroid cartilage 
  • Arytenoid (paired)
  • Cricoid cartilage 

11

Describe the thyroid cartilage 

  • Made up of two laminae 
  • Superior pole is level with C4
  • Provides attachment for the epiglottis and houses the vocal cords 
  • Articulates with the hyoid and cricoid 
  • Main role is in protection of the vocal cords 

12

Describe the arytenoid cartilages

  • It is the posterior attachment for the vocal cords and internal laryngeal muscles 
  • It causes tension-adjustment to allow phonation 

13

Describe the cricoid cartilage 

  • Signet ring shaped 
  • Only complete ring of cartilage 
  • Articulates with the thyroid posteriorly and aretynoid cartilages (it supports these)
  • Fixed to the trachea (kind of like the entrance to the trachea)

14

What is cricoid pressure? 

  • If someone is put under anaesthetic in an emergnecy and they don't have time to fast first then can press on the cricoid cartilage 
  • Because it is a complete ring it compresses the oesophagus 
  • This can prevent stuff from coming up from the stomach and contaminating the airway but allows the airway to remain open 

15

What are the different membranes involved in the larynx?

  • Vestibular ligament 
    • within the vestibular fold (false cord)
  • Vocal ligament
    • within vocal fold (true or vocal cord)
  • Hyoepiglottic ligament 
    • Between hyoid and epiglottis 
  • Quadrangular membrane 
    • Between aretynoid and epiglottis 
    • Also called aryepiglottic membrane 
  • Conus elasticus 
    • Also called cricothyroid ligament 
  • Median cricothyroid ligament 

16

17

Someone has v v bad tonsilitis and infection and swelling are moving rapidly. How do you make the airway safe?

  • Can insert tube through the cricothyroid membrane (cricothyroidectomy) which can be palpated anteriorly 
  • Or percutaenous tracheostomy 
  • (this process is done in acute laryngeal obstruction) 

18

Describe the covering of the vocal and false cord 

  • Lining of true cord is thinner than false cord 
  • Vocal folds, vocalis (v small muscle)- stratified squamous 

19

Describe the attachments of the vestibular and vocal cords 

  • Anterior attachment 
    • Inner surface of thyroid cartilage 
    • This is a fixed point
  • Posterior attachment 
    • arytenoids
    • These are moveable so allows opening and closing of the vocal cords 
    • Arytenoids pivot on the cricoid cartilage when pulled by the laryngeal muscles to move the cords 

20

Describe the position of the cords during respiration, phonation and swallowing 

  • Respiration: abducted 
  • Phonation: partially abducted 
  • Swallowing: adducted 

21

Where are the intrinsic muscles of the larynx found?

  • Within the thyroid cartilage 
  • Except cricothyroid which is an intrinsic muscle as it is involved in phonation but is outside the cartilage (it increases pitch) 

22

What is the only laryngeal muscle which abducts the cords?

Posterior cricoarytenoid (so allows respiration) 

23

Name the muscles of the larynx which allow phonation and describe what movements they allow

  • Posterior cricoarytenoid 
    • Abduction of vocal folds 
  • Lateral cricothyroid 
    • Adduction of vocal folds 
  • Transverse arytenoid 
    • Adduction of vocal folds 
  • Vocalis and thyroarytenoid 
    • Shortening (relaxation) of vocal folds 

24

Which muslces are involved in bringing the epiglottis down to cover the laryngeal opening for swallowing?

  • Aryepiglottis 
  • Thyroepiglottis 

25

What are the different regions of the larynx? 

  • Supraglottis
    • From the lower surface of epiglottis to vestibular folds 
  • Glottis 
    • Level of cords and 1cm below 
    • If stuff goes wrong consequences are worst
  • Subglottis 
    • From glottis to the lower border of the cricoid (this is the end of the larynx as an organ)

26

Nerves and vessels of the larynx run together. What are the nerves? What do they supply? 

  • Superior laryngeal, splits into:
    • Internal- sensory to supraglottis 
    • External- motor to cricothyroid 
  • Recurrent laryngeal 
    • Sensory to subglottis (as it is recurrent then comes back up to supply bottom of larynx)
    • Motor to intrinsic muscles 

27

Which vessels do the nerves of the larynx run with?

  • Superior laryngeal
    • Superior thyroid artery 
  • Recurrent laryngeal 
    • Inferior thyroid artery 

28

29

What membrane does the superior laryngeal nerve pierce?

  • Thyrohyoid membrane 

30

Describe the course of the recurrent laryngeal nerves 

  • Right recurrent laryngeal 
    • Under subclavian
    • Up through tracheoesophageal groove
  • Left recurrent laryngeal 
    • Under arch of aorta 
    • Up through tracheosophageal groove 

31

32

What can recurrent laryngeal nerve palsy be caused by? 

  • Idiopathic 
  • Laryngeal cancer
  • Thyroid disease (benign or mallignant) - this is common 
  • Trauma (including iatrogenic)
    • E.g. thyroidectomy, as nerve is close to the back of the thyroid gland 
  • Cervical lymphadenopathy 
  • Oesophageal cancer
  • Apical lung cancer 
  • Aortic aneurysm- would affect the left 
  • Neuropathic (diabetes)

33

When there is no paralysis what is the position of the vocal cords on phonation and respiration?

  • Respiration 
    • Abducted 
  • Phonation 
    • Adducted 

34

Describe the position of the vocal cords on phonation and respiration in someone with unilateral and bilareral cord paralysis

  • Unilateral paralysis 
    • Paralysed one is always semi-abducted 
    • Normal one moves normally 
  • Bilateral paralysis 
    • Both semi-abducted on respiration (harder to breathe though as smaller space for air)
    • Both adducted on phonation 

35

What are 95% of laryngeal cancers? 

Squamous cell carcinoma 

36

Who gets laryngeal cancer more? Men or women? 

M:F ratio is 5:1

37

What are risk factors for laryngeal cancer? What location of the cancer gives the best prognosis? 

  • Smoking and alcohol are risk factors 
  • Supraglottis has better prognosis than in glottis or subglottis 

38

What can vocal cord cancer look like?

White plaques in the mucous membrane over the cords 

39

What would you expect on a history of someone with laryngeal cancer? 

  • Hoarseness (spread to recurrent laryngeal nerve/larynx)
  • Foreign body sensation in the throat 
  • Dysphagia 
  • Odynophagia (pain on swallowing) 
  • Otalgia (referred pain- vagus, shared innervation)
  • Coughing (aspiration, haemoptysis) 
  • Weight loss
  • Smoking history (pack/years)

40

What is the cervical plexus formed of? Where does it lie? 

  • Formed by anterior primary rami of the first 4 cervical nerves
  • Lies on surface of scalenus medius and levator scapulae, deep to the internal jugular vein and emerges from the posterior border of sternocleidomastoid to lie within the posterior triangle

41

The cerivcal plexus has sensory (cutaneous) and motor branches. What do the sensory branches supply? 

skin of the neck, part of the scalp and ear, supeiror part of thorax 

42

What are the sensory branches of the cervical plexus? 

  • Greater auricular- external ear and skin over parotid gland 
  • Transverse cervical nerve- anterior neck then pierces deep cervical fascia to supply anterolateral skin of the neck and upper sternum 
  • Less occpital- posterosuperior scalp 
  • Supracalvicular nerves- suprascapular fossa and upper thoracic region and sternoclavicular joint 

43

Where is a cervical plexus block done and when? 

  • Erb's point
    • This is where sensory nerves all enter the skin at the middle of the posterior border of sternocleidomastoid 
  • Provides regional anaesthesia for surgery in the neck e.g. thyroidectomy, cervical lymph node excision 

44

When is cervical lymph node excision not done?

  • It patients with co-existing cardiac or respiratory conditions 
  • As cercial plexus block also affects phrenic nerve 

45

Describe the muscular branches of the cervical plexus

  • some form a loop known as the ansa cervicalis which gives rise to nerves supplying most of the 4 paired infrahyoid muscles:
    • Phrenic nerve- motor to diaphragm 
    • Nerves to geniohyoid and thyrohyoid- these travel with hypoglossal nerve 
    • Ansa cervicalis:
      • superior belly of omohyoid
      • Inferior belly of omohyoid
      • Sternohyoid 
      • Sternothyroid 

46

47

As well as the larynx what else is involved in phonation?

  • Pharynx 
  • Oral cavity 
  • Lips 
  • teeth 
  • Tongue 

They modify the sound prouced by the larynx 

48

49

What is the aditus of the larynx?

  • The entrance to the larynx
  • It is formed by the aryepiglottic folds that connect the sides of the epiglottis to the arytenoids 

50

What is the Adam's apple also known as?

Laryngeal prominence (made of thyroid cartilage)

51

What does the crioctracheal membrane connect?

  • It connects all the cartilages 
  • Its upper edge is slightly thickened to form the vocal ligament 

52

Which muscles depress and elevate the larynx?

The infrahyoid and suprahyoid 

53

Describe the action of cricothyroid muscle (only intrinsic muscle of the larynx found outside the larynx)

  • Tenses the vocal cords by tilting the thyroid cartilage on the cricoid cartilage
  • When the vocal cord is tightened a higher sound is made 
  • Unlike the other intrinsic muscles which are innervated by recurrent laryngeal nerve, the cricothyroid is innervated by external laryngeal nerve (branch of superior laryngeal nerve)

54

Movement of which joint caused by the action of the intrinsic muscles of the larynx allows opening and closing of the rima glottidis?

  • Movement of arytenoid cartilage at the cricoarytenoid joint 

55

As well as aryepiglottis and thyroepiglottis pulling the epiglottis over the laryngeal inlet what else aids in this movement?

Contraction of suprahyoid muscles and pharyngeal muscles (pull the larynx upwards, helping further tilt the epiglottis)

56

What is an important relationship to consider when carrying out a thyroidectomy to  help prevent vocal cord paralysis?

  • The close realtionship between recurrent laryngeal nerve (supplies mucosa of subglottis) and internal laryngeal nerve (supplies mucousa of supraglottis, branch of superior laryngeal nerve) with the inferior and superior thyroid arteries 

57

What are benign causes of a hoarse voice?

Infection 

Inflammation 

Vocal cord nodules (singer's nodules)

58

What would damage to the external branch of superior laryngeal nerve cause?

Some weakness of phonation (especially in higher pitch) due to loss of tightening effect of the cricothyroid muscle on the vocal cord 

59

What symptoms are seen on unilateral paralysis of the vocal cords?

Affected cord remains semi-abducted but normal one is quite good at compensating and so normally just some hoarsenss and a weaker cough

60

What symptoms may be seen on bilateral vocal cord paralysis?

  • Both in semi-abducted position (paramedian position)
  • The rima glottis becomes extremely narrow 
  • Affects patient's ability to speak and obstructs movement of air in/out of the trachea 
  • Patients present with difficulty breathing, they may have stridor 

61

What poses a greater threat: complete division of the nerves supplying the vocal cords OR lesions that progressively involve both nerves, or only bruise the nerves?

Lesions that progressively involve both nerves, or only bruise the nerve 

62

If the vocal cords significantly impede air flow what is done?

Emergency tracheostomy 

63

What are carcinomas of the larynx likely to present with?

Voice and/or airway problems, hoarseness of the voice is often the earliest presenting sign of lesions involving the vocal cords 

64

Why is prognosis for laryngeal cancer if it is small and involves the glottis better than if it affects supra- and infra- glottic regions?

  • Glottis has v minimal lymphatic drainage so less likley to spread
  •  Infra and supra glottic regions drain to neck nodes and paratracheal noes respectively so have poorer prognosis 

65

What are the suprahyoid muscles and their general action and innervation?

  • go between hyoid and skull/mandible
  • Raise the hyoid e.g. in swallowing, chewing and speaking
    • Stylohyoid- CN VII 
    • digastric
      • Posterior belly- CNVII
      • Anterior belly- CNV3
  • Mylohyoid- CNV3
  • Geniohyoid- anterior ramus of C1 carried by hypoglossal nerve 

66

What are the infrahyoid muscles? general action? innervation?

  • Attach hyoid to inferior structures and depress hyoid
  • also called strap muscles 
  • Innervated by C1-C3 on ansa cervicalis of cervical plexus 
    • Sternohyoid 
    • Omohyoid
      • Superior (anterior border of carotid triangle) and inferior belly
    • Thyrohyoid
    • Sternothyroid 
    •  

67

What must you do with infrahyoid muscles when doing thyroidectomy?

Retract them to one side as they lie anterior to the gland