Airway Anatomy Flashcards
Muscles that tense the vocal cords?
elongates
Cricothyroid
(“cords tense”)
think of the cricothyroid as the tuning fork for the vocal cords :)
Muscles that relax the vocal cords?
Thyroarytenoids
“They Relax”
Muscles that ABduct the vocal cords?
Posterior Cricoarytenoid
“pull cords apart”
Muscles that ADduct the vocal cords?
Lateral Cricoarytenoids
“let’s close airway”
The superior laryngeal nerve branches off what nerve?
Vagus nerve
The superior laryngeal nerve divides into what two branches?
internal and external branch of the SLN.
The internal branch of the SLN penetrates what membrane?
The internal branch penetrates the thyrohyoid membrane.
The external branch of the SLN enters which muscle?
The external branch enters the cricothyroid muscle.
The RLN branches off of the vagus nerve inside of what structure?
inside the thorax
What does the right RLN loop under and what does the L RNL loop under?
The right RLN loops under the subclavian artery.
The left RNL loops under the aortic arch.
Which RLN is more susceptible to injury?
The left due to looping under the aortic arch.
Which branch of the SLN innervates the cricothyroid muscle?
external branch (motor)
Which nerve innervates the posterior side of the epiglottis to the top side of the vocal cords?
SLN internal branch
Which nerve innervates the cricothyroid muscle?
SLN external branch
4 nerves that innervate the sensory portion of the airway?
trigeminal
glossopharyngeal
SLN
RLN
Injury to the trunk of the SLN or the external branch can cause what and why?
can cause hoarseness, because the vocal cords can not tense.
Unilateral injury to the RLN results in what kind of paralysis? Does it cause Respiratory distress?
results in paralysis of the ipsilateral vocal cord abductors, this does not cause respiratory distress.
Explain acute bilateral injury to the RLN and what must be done?
Results in bilateral paralysis of the vocal cord abductors. This allows for unopposed tensing action by the cricothyroid muscle. Therefore a patient with an acute injury to BOTH RLNs is at risk for stridor and respiratory distress.
Patient requires intubation or surgical airway.
Chronic injury to the RLN, tell me about it?
well tolerated and does not cause respiratory distress.
What are some conditions that can cause Left side only RLN injury?
Aortic arch aneurysm
Thoracic tumor
Left atrial enlargement (mitral stenosis)
PDA ligation
Glossopharyngeal Block, how to tell when you are too deep, when to redirect, how much LA is injected, and what are the risks?
aspiration of air = too deep
when you aspirate blood you should withdrawal and redirect medially.
1-2ml of LA on both sides injected
5% incidence of intracarotid injection with a risk of seizures
Where do you inject for a glossopharyngeal block?
needle is inserted at the base of the palatoglossal arch (anterior tonsillar pillar) depth of 0.25-0.5 cm.
Insertion direction of the needle during a transtracheal block?
needle is advanced in a caudal direction as it penetrates the cricothyroid membrane.
During a transtracheal block what should the patient do before injection of LA, and what does this cause?
After aspiration and before injection the patient should take a deep breath, during the deep breath 3-5ml of LA is injected to the tracheal lumen this causes the patient to cough and sprays LA up through the cords.
The adult larynx extends from what vertebrae to what vertebrae?
C3-C6
name the three paired cartilages and the three unpaired cartilages
Paired are : corniculate
arytenoid
cuneiform
unpaired are:
Thyroid
cricoid
Epiglottis
Can you see the arytenoids during direct laryngoscopy?
No
What two diseases can significantly decrease the movement of the arytenoids and possibly cause airway obstruction?
rheumatoid arthritis and Lupus
the arytenoids create a ball and socket joint with the cricoid cartilage allowing the vocal cords to move and function
What membrane is punctured during a cricothyroidotomy for emergent securement of the airway?
cricothyroid membrane
know the location for a hotspot question, below the thyroid and above the cricoid
What is the largest cartilage in the larynx?
Thyroid
What is the the only complete cartilaginous ring in the airway?
Cricoid
What is the narrowest part of the pediatric airway? (controversial answer)
The answer will be either vocal cords or cricoid ring.
In the anesthetized child the narrowest region is the vocal cords BUT they are soft and can be stretched by an ETT placed between them.
The cricoid ring is fixed and can not be stretched or increased in diameter, it can however be reduced by edema that results from an ETT that is too large, multiple intubations, prolonged intubation etc.
So hopefully both will not be listed on boards as an answer and if they are maybe the question will clue you in.