airway anatomy Flashcards
cricothyroid does what to the airway
cords tense (which elongates)
what do the vocal cords attach to anteriorly and posteriorly
anteriorly: thyroid
posteriorly: aretynoids
all extrinsic laryngeal muscles end in
-hyoid (except digastric)
muscles that depress the larynx include (3)
thyrohyoid
omohyoid (superior and posterior belly)
sternohyoid
muscles that elevate the larynx include (8)
digastric (anterior and posterior belly)
mylohyoid
stylohyoid
sternohyoid and omohyoid
thyrohyoid
sternothyroid
omohyoid (superior belly)
sternohyoid
where does the superior laryngeal internal nerve provide sensory innervation
posterior side of epiglottis to level of vocal cords
where does the superior laryngeal external nerve provide motor innervation
cricothyroid muscle (tenses vocal cords)
acute injury to SEM branch causes what
hoarseness but not respiratory distress because cord can not be tensed
where does the RLN provide sensory innervation
below the vocal folds to the trachea
where does the RLN provide motor innervation
all intrinsic laryngeal muscles except cricothyroid
risk factors specific to left RLN injury (more frequent) include (4)
PDA ligation, left atrial enlargement (secondary to mitral stenosis), aortic arch aneurysm, thoracic tumor
what happens with acute bilateral RLN injury
tensing action of cricothyroid muscles act unopposed, will be in respiratory distress. presents similarly to laryngospasm.
3 cranial nerves that innervate upper airway
glossopharyngeal
trigeminal
vagus
3 branches of trigeminal nerve (CN5) and what they innervate
V1 ophthalmic aka anterior ethmoidal (nares and anterior 1/3 of nasal septum)
V2 maxillary aka sphenopalatine (turbinates and septum)
V3 mandibular aka lingual (anterior 2/3 of tongue)
sensory innervation of glossopharyngeal nerve (CN9)
oropharynx and anterior side of epiglottis. this includes soft palate, tonsils, posterior 1/3 of tongue, vallecula, anterior side of epiglottis
afferent and efferent limbs of gag reflex
afferent: glossopharyngeal
efferent: vagus
at the level of the ______, the SLN divides into internal and external branches
hyoid
the internal branch of the SLN penetrates which membrane
the thyrohyoid membrane between the greater cornu of the hyoid bone and the superior horn of the thyroid cartilage
the right RLN loops under the __________ while the left RLN loops under the ____________
right RLN loops under subclavian artery while left RLN loops under the aortic arch
considerations for glossopharyngeal nerve block
- insert needle at base of palatoglossal arch (anterior tonsilar pillar) to a depth of .25-.5cm. (aspiration of air means needle is too deep. aspiration of blood means withdraw from carotid and re direct medially)
- insert 1-2mL of LA
considerations for superior laryngeal nerve block
- anesthetic injected at inferior border of greater cornu of hyoid bone
- Once 1mL is injected outside of the thyrohyoid membrane, 2-3mL is injected 3mm deep to the thyrohyoid membrane. (aspiration of air means needle is too deep)
considerations for RLN block
- puncture CTM and advance needle in caudal direction
- after aspiration, but before injection, tell the patient to take a deep breath. during that inspiration, inject 3-5mL of LA into the tracheal lumen. the patient will cough and it will go upwards towards the cords.
the adult larynx lies anterior to which cervical vertebrae?
C3-C6
3 paired and 3 unpaired laryngeal cartilages
paired: aretynoid, corniculate, cuneiform
unpaired: thyroid, epiglottis, cricoid
the only bone in the body that does not articulate with another bone
hyoid
narrowest fixed region of airway in kids less than 5 years
cricoid ring
narrowest dynamic region of airway in kids less than 5 years
vocal cords
laryngospasm pathway (afferent and efferent limbs)
afferent limb: internal branch of SLN
efferent limb: external branch of SLN (cricothyroid) and RLN (lateral cricoaretynoid, thyroaretynoid- both close glottis)
pre anesthetic risk factors of laryngospasm (5)
<1 year old
exposure to second hand smoke
GERD
active or recent URI (<2w)
reactive airway disease
order in which you should treat laryngospasm
- FiO2 100%
- remove noxious stimuli
- deepen anesthetic
- CPAP 15-20cmH2O
- open airway
- larsens maneuver
- administer succ
dose of succ IV and IM for laryngospasm (adult)
IV 1mg/kg
IM 4mg/kg (also for children)
dose of succ IV and IM for laryngospasm (neonates/infants)
IV neonate or infant 2mg/kg
IM neonate or infant 5mg/kg
when administering succ to a kid under 5, you should co administer
atropine .02mg/kg
anesthesia induced obstruction at the level of the tongue is related to
geniglossus muscle relaxation (most common)
anesthesia induced obstruction at the level of the soft palate is related to
tensor palatine muscle relaxation
what do hyoid muscles help keep open in upper airway
hyopharynx
angle of right mainstream bronchus
25 degrees
angle of left mainstream bronchus
45 degrees
where does trachea begin and end
C6 to T4/5
how many cm long is trachea
10-13cm
type of cells in trachea
ciliated columnar epithelium
sensory innervation to trachea
vagus nerve
blood supply to trachea (4 arteries)
inferior thyroid artery
superior thyroid artery
bronchial artery
internal thoracic artery
what does the carina correspond to
angle of louis
type of cells in carina
ciliated columnar epithelium
type of cells in mainstem bronchi
cuboidal epithelium
what allows air movement between alveoli
pores of Kohn
what type of cells in alveoli
squamous epithelium
type 1 pneumocytes
provide surface for gas exchange.
-flat squamous cells
-cover 80% of alveolar surface
-form tight junctions
type 2 pneumocytes
produce surfactant
-resistant to O2 toxicity
-capable of cell division
-can produce type 1 cells
type 3 pneumocytes
macrophages
-fight lung infections
-produce inflammatory response
what is present in alveoli of smokers and patients with acute lung injury
neutrophils
distance from incisors to larynx then larynx to carina
13cm then 13cm (26cm total)
in children less than 3 years old, what is the angle of the mainstem bronchi on both sides
55 degrees
what type of cells decrease as airway bifurcates
goblet cells
ciliated cells
