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
