Airway anatomy Flashcards

1
Q

Name three functions of the nose?

A
  1. Warm
  2. Humidify
  3. Filter
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2
Q

What type of epithelium line the respiratory tract?

A

Nasal mucosa to bronchi - Pseudostratified columnar epitehlium with goblet cells

Bronchioles - simple cuboidal epithelium

Alveoli - Simple squamous epithelium

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3
Q

What is the function of the respiratory mucosa?

A

Formation of the mucociliary escalator and to ensure warming and near 100% humidification of air.

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4
Q

What are choanae?

A

Posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat.

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5
Q

Where is the widest part of the nasal airway?

A

Inferior to the inferior turbinate

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6
Q

What are the advantages of nasal intubation?

A
  1. leaves oral cavity clear for oral surgery

2. ICU patients - better tolerated.

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7
Q

What are the disadvantages of nasal intubation?

A
  1. More difficult
  2. Nose bleeds
  3. Mucosal injury with creation of a false passageway into the cranium.
  4. Long-term: infection in paranasal air sinuses
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8
Q

What two bones make up the hare palate and what is their orientation in the hard palate?

A

Anterior - palatine processes of the maxillary bone

Posterior - horizontal plates of the palatine bone.

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9
Q

From where does the soft palate originate?

A

Suspended from the posterior aspect of the hard palate and blends with the pharyngeal wall laterally and forms the uvula in its central portion

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10
Q

Why doesn’t a nasopharyngeal airway stimulate the gag reflex?

A

Contact with the palate, tonsil, posterior part of the tongue or the posterior pharyngeal wall elicit the gag reflex. If the NP airway does not extend beyond the tip of the soft palate, then the gag reflex will not be stimulated

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11
Q

What are the afferent and efferent nerves for the gag reflex?

A

Afferent - glossopharyngeal nerve

Efferent - vagus nerve

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12
Q

What makes up the pharynx

A

Nasopharynx
Oropharynx
Laryngopharynx

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13
Q

In what part of the pharynx do fish bones often lodge?

A

In the piriform fossae which are recesses within the laryngopharynx on either side of the posterior bulging larynx

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14
Q

Where are the adenoids located? What complications can occur regarding these structures.

A

Posterior to the nasal cavity on roof and posterior wall of the nasopharynx. They may become a site of bleeding following nasal intubation in children.

Obstructive sleep apnoea can occur with adenoid hypertrophy

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15
Q

What are the palatoglossal and the palatopharyngeal aches collectively known as and what structure lies between these two arches bilaterally?

A

The pillars of the fauces - between these structures are the palatine tonsils or ‘tonsils’

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16
Q

What are the clinical implications related to the palatine tonsils?

A
  1. Childhood hypertrophy - tonsillectomy indicated for OSA and recurrent infection
  2. Large tonsils may cause airway obstruction after induction of anaesthesia
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17
Q

Describe the sensory nerve supply to the tonsil and suggest the most efficient regional anaesthetic technique.

A

Sensory nerve supply is from branches of three different nerves:

  1. glossopharyngeal n.
  2. maxillary n.
  3. mandibular n.

Infiltration of local anaesthetic into the tonsillar bed is more effective than attempting nerve blockade

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18
Q

How is aspiration prevented during swallowing?

A
  1. Reflex closure of the laryngeal sphincter (vocal cords close)
  2. Reflex upward movement of the larynx behind the tongue
  3. Reflex inhibition of breathing
  4. Epiglottis may act as a lid to the larynx
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19
Q

What procedures remove the airway protective reflexes that occur in swallowing?

A
  1. General anaesthesia
  2. Application of topical anaesthetic to larynx
  3. Neurological injury
20
Q

Where in the neck is the larynx located

A

Midline opposite the 3rd to the 6th cervical vertebrae closely related to the carotid arteries and jugular veins connecting pharynx to trachea

21
Q

Name the three unpaired cartilages of the larynx

A

Thyroid cartilage
Cricoid cartilage
Epiglottis

22
Q

Name the paired cartilages of the larynx

A

Arytenoid
Corniculate
Cuneiform

23
Q

What is the function of the hyoid bone

A

Greater movement of tongue and larynx

24
Q

What are three functions of the larynx

A

Breathing
Phonation
Protection of lower respiratory tract

25
Q

How many types of cartilage are there? Name and define them.

A

There are 3 types of cartilage:

  1. Hyaline cartilage (most widespread: ribs, nose, larynx, trachea and is a precursor for bone)
  2. Fibrous cartilage (the only type of cartilage that contains type I collagen as well as the usual type 2: pubic symphysis and intervertebral discs)
  3. Elastic cartilage (elastic fibers - with elastin - and collagen 2 - eustachian tube and epiglottis)
26
Q

Which cartilage in the larynx is hyaline cartilage

A

Thyroid
Cricoid
Arytenoids

27
Q

Which cartilage in the larynx consist of elastic cartilage?

A

Epiglottis
Coniculate (paired - articulate with arytenoids at bases)
Cuneiform (paired - no attachment to other cartilage)

28
Q

Name the extrinsic membranes and ligaments of the larynx

A

Thyrohyoid ligament

  • lateral thyrohyoid lig.
  • median thyrohyoid lig.

Cricothyroid ligment
- Median cricothyroid ligament

Tracheocricoid ligament

29
Q

Name the intrinsic membranes and ligaments of the larynx

A

Elastic cone - paired - extends superiorly from the lateral aspects of the cricoid cartilage to the vocal lig.

Vocal ligament - extends from the the angle of the thyroid prominence to the vocal process of the arytenoid cartilage covered by the vocal folds (mucosa) - yellow elastic tissue.

Quadrangular membrane - square shaped layer of submucosa extending from lateral aspect of epiglottis to arytenoid cartilages - superior border defines the aryepiglottal fold

Vestibular ligament - formed by the thickened free edge of the inferior margin of the qaudrangular ligament enveloped by the vestibular fold

30
Q

What is the narrowest part of the airway in the adult

A

Rima glottidis (space between the true vocal cords)

Space between vestibular folds is called the rima vestibuli

31
Q

What is the function of the extrinsic muscles of the larynx

A

These muscles work with other muscles attached to the hyoid bone to move the larynx up and down during swallowing

32
Q

What is the function of the intrinsic muscles of the larynx?

A
  1. Open vocal cords during inspiration
  2. close vocal cords and laryngeal inlet during swallowing
  3. Alter cord tension during phonation
33
Q

What is the function of the posterior cricoarytenoid muscle and what is the nerve supply to this muscle

A

aBduction of the cords by pulling the posterior ends of the arytenoid cartilages together medially –> pivoting and abduction of the cords

The external division of the superior laryngeal nerve

34
Q

What is the function of the lateral cricoarytenoids and transverse arytenoids?

A

aDduction of the cords by pulling the posterior aspect of the pivoting arytenoids away from each other

35
Q

What is the function of the aryepiglottics and the thyroepiglottics

A

These close the laryngeal inlet during swallowing

36
Q

What is the function of the cricothyroid muscles

A

To tilt the thyroid cartilage anteriorly to tense the cord for higher pitched phonation

37
Q

What is the function of the thyroarytenoids and vocalis

A

Thyroarytnoids - relax the cords

Vocalis - fine adjustments of the cords

38
Q

Which nerve is responsible for the sensory supply to the larynx above the vocal cords?

A

Superior laryngeal nerve (internal branch) (a branch of the vagus nerve)

The external branch provides the motor supply to the cricothyroid muscle

39
Q

Which nerve is responsible for the sensory supply to the larynx below the level of the vocal cords?

A

Recurrent laryngeal nerve (also a branch of the vagus nerve)

40
Q

Stimulation of which nerve might induce vagal reflexes during laryngoscopy

A

Internal branch of the superior laryngeal nerve which provides the sensory supply to the vallecula

41
Q

Which nerve supplies all the intrinsic muscles of the larynx except the cricothyroid muscle

A

Recurrent laryngeal nerve

42
Q

Describe the path of the right recurrent laryngeal nerve

A

The vagus nerve dips into the thorax first –> Under right subclavian artery to ascend into the larynx in the groove between the oesophagus and trachea

43
Q

Describe the path of the left recurrent laryngeal nerve

A

The vagus nerve dips into the thorax first –> Under the aortic arch to ascend into the larynx in the groove between the oesophagus and the trachea

44
Q

What happens when the superior laryngeal nerve is damages

A
  1. Hoarse voice (loss of tensor function of the cords - cricothyroid)
  2. Increase aspiration risk: less sensation above the cords
45
Q

What happens with unilateral damage to the recurrent laryngeal nerve

A
  1. Hoarse voice with slight recovery - compensation of contralateral cord
  2. Ineffective cough (glottis cannot close completely - no adequate pressure build up)
  3. Increased risk of aspiration - infraglottic sensory loss
46
Q

What happens if there is damage to both recurrent laryngeal nerves

A

Severe respiratory distress with stridor as the flaccid vocal cords flap together. Urgent intubation required with tracheostomy likely to follow

47
Q

why should cricothyroidotomy only be used as a temporary airway?

A

Should be converted to tracheostomy within 72 hours to reduce risk of subglottic stenosis