Unit 1 Respiratory 1: Airway Anatomy Flashcards

1
Q

What are the intrinsic muscles of the larynx used for?

A

Phonation and/or vocal cord movement

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2
Q

What are the extrinsic muscles of the larynx used for?

A

Support the larynx inside the neck

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3
Q

Where do the true vocal cords attach anteriorly and posteriorly?

A

Anteriorly: to the thyroid cartilage
Posteriorly: to the arytenoid cartilage

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4
Q

Cricothyroid:
Function
Primary outcome of muscle contraction
Innervation

A

Function: adjusts length (tension) of the vocal ligaments
Primary outcome of muscle contraction: elongates (tenses)
Innervation: SLN (external)

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5
Q

Vocalis:
Primary outcome of muscle contraction
Innervation

A

Function: adjusts length (tension) of vocal ligaments
Primary outcome of muscle contraction: shortens (relaxes)
Innervation : RLN

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6
Q

Thyroarytenoid:
Primary outcome of muscle contraction
Innervation

A

Function: adjusts length (tension) of vocal ligaments AND glottic diameter
Primary outcome of muscle contraction: shortens (relaxes) AND adducts vocal folds (narrows glottis)
Innervation: RLN

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7
Q

Lateral cricoarytenoid:
Function
Primary outcome of muscle contraction
Innervation

A

Function: glottic diameter
Primary outcome of muscle contraction: adducts vocal folds (narrows glottis)
Innervation : RLN

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8
Q

Posterior cricoarytenoid
Function
Primary outcome of muscle contraction
Innervation

A

Function: glottic diameter
Primary outcome of muscle contraction: abducts vocal folds (widens glottis)
Innervation: RLN

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9
Q

Sphincter function of aryepiglottic? Interarytenoid?

A

Aryepiglottic: closes laryngeal vestibule - RLN
Interarytenoid: closes posterior commisure of glottis - RLN

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10
Q

What 6 extrinsic muscles elevate the larynx in the neck for breathing and swallowing?

A
Stylohyoid
Geniohyoid
Mylohyoid
Thyrohyoid
Digastric
Stylopharyngeus
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11
Q

What 3 extrinsic muscles depress the larynx within the neck for breathing and swallowing?

A

Omohyoid
Sternohyoid
Sternothyroid

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12
Q

What nerve does the SLN branch off of and where?

A

SLN branches off of the vagus nerve just beyond the jugular foramen at the skull base

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13
Q

At what level does the SLN divide? What does it divide into?

A

At the level of the hyoid, the SLN divides into the internal and external branches

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14
Q

What does the internal branch of the SLN penetrate?

A

The thyrohyoid membrane between the greater Cornu of the hyoid bone

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15
Q

Where does the external branch enter?

A

The cricothyroid muscle

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16
Q

What does the RLN branch off of and where?

A

The RLN branches off of the vagus nerve inside the thorax

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17
Q

Both the right and left RLNs make loops before ascending tracheoesophageal groove to joint larynx, where do each loop?

A

Right RLN: loops under the subclavian artery

Left RLN: loops under the aortic arch

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18
Q

Which RLN is more susceptible to injury and why?

A

Due to its location in the thorax the left RLN is more susceptible to injury

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19
Q

What 4 nerves provide sensory innervation of the airway?

A

Trigeminal (CN V)
Glossopharyngeal (CN IX)
Superior laryngeal
Recurrent laryngeal

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20
Q

Describe Trigeminal (CN V) sensory innervation of the airway

A

V1: ophthalmic (anterior ethmoidal) - nares & anterior 1/3 of nasal septum
V2: maxillary (sphenopalatine) - turbinates & septum
V3: mandibular (lingual) - anterior 1/3 of tongue

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21
Q

Describe the glossopharyngeal (CN IX) sensory innervation of the airway

A
Soft palate
Oropharynx
Tonsils
Posterior 1/3 of tongue
Vallecula
Anterior side of epiglottis
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22
Q

What is the afferent limb of the gag reflex?

A

Glossopharyngeal (CN IX)

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23
Q

Describe the superior laryngeal nerve sensory innervation of the airway

A

Internal branch: posterior side of the epiglottis to level of the vocal cords

The external branch provides motor only, not sensory innervation

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24
Q

Describe the recurrent laryngeal nerve sensory innervation of the airway

A

Below level of vocal cords to trachea

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25
Q

Describe the superior laryngeal nerve motor innervation of the larynx

A

External branch: cricothyroid muscle - tense vocal cords

Internal branch provides sensory innervation only

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26
Q

Describe recurrent laryngeal nerve motor innervation of the larynx

A

All intrinsic muscles except cricothyroid

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27
Q

SLN injury causes what?

A

Hoarseness because the vocal cords can’t be tensed

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28
Q

Injury to the RLN causes what?

A

Depends on unilateral or bilateral injury:
Unilateral - results in paralysis of the ipsilateral (same side) vocal cord abductors and does not cause respiratory distress
Bilateral - results in bilateral paralysis of the vocal cord abductors, tensing action of the cricothyroid muscles act unopposed -> stridor and respiratory distress

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29
Q

What about chronic injury of the RLN?

A

Well tolerated and does not cause respiratory distress

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30
Q

Name 6 things that can cause RLN injury to either side

A
External pressure from ETT tube
External pressure from LMA
Thyroid surgery
Parathyroid surgery
Neck stretching 
Tumor
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31
Q

Name 4 things that can cause injury to the right RLN only

A

PDA ligation
Left atrial enlargement (mitral stenosis)
Aortic arch aneurysm
Thoracic tumor

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32
Q

Name the 3 infiltration airway blocks

A

Glossopharyngeal block
Superior laryngeal block
Transtracheal block

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33
Q

Glossopharyngeal block:
Needle insertion site
Aspiration
Injected amount

A

Needle insertion site: at the base of the palatoglossal arch (anterior tonsillar pillar) at a depth of 0.25 - 0.5 cm
Aspiration: air - too deep; blood - withdrawal and redirect medically (carotid is very close)
Injected amount: 1 - 2 mL of LA on both sides

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34
Q

SLN block:
Needle insertion site
Aspiration
Injected amount

A

Needle insertion site: inferior border of the greater Cornu of the hyoid bone
Aspiration: air - too deep
Injected amount: 1 mL injected above the thyrohyoid membrane then 2 mL injected 2 - 3 mm beneath it

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35
Q

Transtracheal block:
Needle insertion site
Aspiration
Injected amount

A

Needle insertion site: advance needle in a caudal direction as it penetrates the cricothyroid membrane
Aspiration: before injection ask patient to take a deep breath
Injected amount: during inspiration 3 - 5 mL, cough sprays LA up through the cords

36
Q

The adult larynx extends from what level to?

A

C3 - C6

37
Q

What are the 3 paired and 3 unpaired cartilages of the larynx?

A

paired: corniculate, aryteniod, cuneiform
unpaired: epiglottis, thyroid, cricoid

38
Q

What forms the main support of the larynx and attaches to the thyroid cartilage via the thyrohyoid ligament?

A

Hyoid bone

39
Q

What attaches the larynx (specifically the thyroid cartilage) to the hyoid bone?

A

The thyrohyoid membrane

40
Q

What attaches the cricoid and thyroid cartilages? What significance does this have in an airway emergency?

A

Cricothyroid membrane.
This is punctured during cricothyroidotomy to emergency secure an airway.
This is also where the needle for a Transtracheal block is placed.

41
Q

What cartilages provide structure to the aryepiglottic folds? Which are lateral to the other?

A

Corniculate and cuneiform.

The cuneiform are lateral to the corniculates.

42
Q

What often is misidentified as arytenoids during DVL?

A

Corniculate and cuneiform. You can not see the arytenoids on DVL.

43
Q

The base of each arytenoid cartilage articulates with the cricoid cartilage to form a ball and socket joint that allows the arytenoids to rotate, pivot, and glide; what may cause airway obstruction in relation to this synovial joint?

A

The movement of the arytenoids can be significantly restricted by RA and systemic lupus erythematosus -> airway obstruction

44
Q

What provides a mechanical barrier between the pharynx and the laryngeal opening?

A

Epiglottis

45
Q

What is the space between the base of the tongue and the anterior side of the epiglottis?

A

Vallecula

46
Q

What ligament connects the epiglottis to the thyroid cartilage?

A

Thyroepiglottic ligament

47
Q

What cartilage provides structure and protection to the larynx?

A

Thyroid

48
Q

What is the largest cartilage in the larynx?

A

Thyroid

49
Q

What forms the Adam’s apple?

A

Thyroid cartilage

50
Q

What is the most caudal part of the larynx?

A

Cricoid cartilage

51
Q

What is the narrowest part of the adult airway? Pediatric?

A

Adult: vocal cords
Pediatric: Vocal cords (dynamic), cricoid (fixed)

52
Q

Laryngeal shape in the adult? Pediatric?

A

Adult: cylinder
Pediatric: funnel

53
Q

Define laryngospasm. What can it lead to?

A

Sustained and involuntary contraction of the laryngeal musculature that results in the inability to ventilate.
Often outlasts the stimulus.
May result in complete airway obstruction, negative pressure pulmonary edema, gastric aspiration, cardiac arrest, and death

54
Q

In what population is laryngospasm more common?

A

Children, especially < 1 year of age

55
Q

List 5 pre-anesthetic risks for laryngospasm:

A
Active or recent URI (< 2 weeks)
Exposure to second hand smoke
Reactive airway disease
GERD
Age < 1 year
56
Q

List 5 in the OR risks for laryngospasm:

A
Light anesthesia particularly with concurrent airway manipulation 
Saliva or blood in the upper airway
Hyperventilation
Hypocapnia
Surgical procedures involving the airway
57
Q
Reflex pathway of laryngospasm:
Afferent limb
Efferent limb
Tensions of the vocal cords
Adduction of the vocal cords
A

Afferent limb: SLN internal branch
Efferent limb: SLN external branch and RLN
Tensions of the vocal cords: cricothyroid
Adduction of the vocal cords: lateral cricoarytenoid and thyroarytenoid

58
Q

Signs of laryngospasm:

A

Inspiratory stridor
Suprasternal and supraclavicular retractions during inspiration
“Rocking horse” appearance of the chest wall
Increased diaphragmatic excursion
Lower rib flailing

59
Q

8 factors that reduce the likelihood of laryngospasm

A

Avoidance of airway manipulation during light anesthesia
CPAP 5 - 10 cmH2O during inhalation induction and post extubation
Remove pharyngeal secretions and blood before extubation
Deep extubation or fully awake - no in-between
Laryngeal lidocaine - DOA ~ 30 min
IV lidocaine before extubation
Hypercapnia/hypoventilation
PaO2 < 50 mmHg

60
Q

6 interventions for laryngospasm

A
  1. FiO2 100%
  2. Remove noxious stimuli
  3. Deepen anesthesia
  4. CPAP 15 - 20 cmH2O while instituting airway maneuvers - head extension, chin lift, Larson’s maneuver)
  5. IV Sux: 2 mg/kg (neonate or infant) or 1 mg/kg child or adult
    IM Sux: 5 mg/kg (neonate or infant) or 4 mg/kg child or adult
  6. Children < 5 years old should receive atropine 0.02 mg/kg with Sux to prevent bradycardia
61
Q

Where will IM sux produce the fastest onset?

A

Submental

62
Q

Define Larson’s maneuver. What are the 2 goals? How long should it be applied?

A

Application of firm pressure bilaterally to the laryngospasm notch (behind the earlobes) towards the skull base.
It displaces the mandible anteriorly to help open the airway.
It often breaks larngospasm by causing the lightly anesthetized patient to sigh.
Apply for 3 - 5 seconds, release for 5 - 10 seconds and repeat.

63
Q

What is valsalva’s maneuver? What risk is associated with it?

A

Exhalation against a closed glottis or obstruction.

Risk: increased pressure in the thorax, abdomen, and brain

64
Q

What is Muller’s maneuver? What risk is associated with it?

A

Inhalation against a closed glottis or obstruction.

Risk: subatmospheric pressure in thorax -> negative pressure pulmonary edema

65
Q

What are the 3 borders of the larngospasm notch?

A

Posterior: mastoid process
Anterior: ramus of the mandible
Superior: skull base

66
Q

The upper airway extends from?

A

Mouth/nares to cricoid cartilage

67
Q

Tensor palatine muscle relaxation will most likely cause airway obstruction at which level?

A

Soft palate

Tensor palatine opens the nasopharynx

68
Q

Genioglossus muscle relaxation will most likely cause airway obstruction at which level?

A

Tongue

Genioglossus opens the oropharynx

69
Q

Hyoid muscle relaxation will most likely cause airway obstruction at which level?

A

Epiglottis

Hyoid muscles open the hypopharynx

70
Q

The lower airway begins where?

A

At the trachea and ends at the alveoli

71
Q
Trachea:
Begins/ends
Width
Length
Epithelium
A

Begins/ends: begins at C6 and ends at T4-5 the carina
Width: 2.5 cm
Length: 10 - 13 cm
Epithelium: ciliated columnar epithelium

72
Q

What provides the sensory innervation of the trachea?

A

Vagus nerve

73
Q

What arteries provide blood supply to the trachea?

A

Inferior thyroid a.
Superior thyroid a.
Bronchial a.
Internal thoracic a.

74
Q

Where is the carina? What level does it correspond with? What type of epithelium is there?

A

T4-5
Angle of Louis
Ciliated columnar epithelium

75
Q

Mainstem Bronchi:
Right length and angle
Left length and angle
Epithelium present

A

Right 2.5 cm long; 25 degree take off
Left 5 cm long; 45 degree take off
Cuboidal epithelium

76
Q

How many alveoli does one have by age 9 year?

A

300 million

77
Q

What type of epithelium are the alveoli?

A

Squamous epithelium

78
Q

What allows air movement between the alveoli

A

Pores of Kohn

79
Q

Name the 3 types of pneumocytes and their functions

A

Type I cells: provide surface for gas exchange

  • flat squamous cells
  • cover ~ 80% of alveolar surface
  • form tight junctions

Type II cells: produce surfactant

  • resistance to oxygen toxicity
  • capable of cell division
  • can produce type I cells

Type III cell: are macrophages

  • fight lung infections
  • produce inflammatory response
80
Q

What type of cells are present in the alveoli in smokers and patients with acute lung injury?

A

Neutrophils

81
Q

Distance from incisors to larynx?

A

13 cm

82
Q

Distance from larynx to the carina?

A

13 cm

83
Q

Distance from incisors to carina?

A

26 cm

84
Q

How do the bronchi angles change in children up to 3 years old?

A

Both bronchi take off 55 degrees from the long axis of the trachea

85
Q

What 3 things increase as the airway bifurcates?

A

Number of airways
Cross-sectional area
Muscular layer

86
Q

What 4 things decrease as the airway bifurcates?

A

Airflow velocity
Amount of cartilage
Goblet cells
Ciliated cells