Airway Anatomy Flashcards
Components of the upper airway
Nose, mouth, pharynx, hypopharynx, larynx
Components of pharynx and location
Extends from nose to cricoid cartilage in three components
Nasopharynx, oropharynx, hypopharynx
Nasopharynx
Location and structures
Lies anterior to C1
Bound superiorly by base of skull and inferiorly by soft palate
Contains nasal septum, turbinates, and adenoids
What impedes airflow in nasopharynx
Tonsillar lymphoid structures
Oropharynx
Location
Lies at C2-C3
Bound superiorly by soft palate and inferiorly by epiglottis
Opens into mouth anteriorly through the anterior and posterior tonsillar pillars
What is the major source of oropharyngeal obstruction and why
The tongue due to decreased genioglossus muscle tone (CNXII - hypoglossal)
Hypopharynx
Location
C5-C6
Lies posterior to larynx and leads to esophagus
Bound by superior border of epiglottis and inferior border of cricoid cartilage (C5-C6)
What is the purpose of the upper esophageal sphincter
Lies at lower edge of hypopharynx and acts as a barrier to regurgitation in the conscious patient
Waldeyer’s Tonsillar Ring
Lymphoid tissue ring in pharynx that is at high risk for bleeding, especially with nasal intubation
Made up of:
- Pharyngeal tonsils (adenoids) - nasopharynx
- Tubal tonsils - between pharyngeal and palatine
- Palatine tonsils - oropharynx (the ones we think of as tonsils)
- Lingual tonsils - base of tongue
Larynx location
Epiglottis to lower lever of cricoid cartilage (C5-c6 in adults)
Sits at the junction of the airway and esophagus
Posterior border = mucus membrane which extends between the arytenoid cartilage and laterally by the aryepiglottic folds (aka false cords)
Larynx components and cartilages
Cartilagenous skeleton held together by ligaments, muscles, NINE cartilages, and hyoid bone
The nine cartilages are (Three individual and three paired)
- thyroid
- cricoid - C6
- epiglottic
- corniculate pair
- aryetnoid pair
- cuneiform pair
Epiglottis
Base of tongue, separates hypopharynx from larynx
On either side of glossepiglotic fold is the vellecula
Protects against aspiration because it covers trachea while swallowing
VASCULAR AREA
Arytenoids
Lie posterior and vocal cords attach to these
Pyramidal
Vocal cords attachment points
Anteriorly = thyroid Posteriorly = arytenoids
Glottic opening
The triangular fissure between the cords
The narrowest portion of an adult airway (6-9mm - can be stretched to 12mm)
What is the narrowest part of the pediatric airway
Just below the cords at the cricoid ring
What is the largest cartilage of the larynx
Thyroid cartilage
Cricoid cartilage location and special fact
The only complete tracheal ring
Sits at c6
Thyrohyoid membrane
Connects thyroid cartilage to hyoid bone
Where does the internal branch of the SLN penetrate the thyrohyoid membrane
And the level of the cornu of the hyoid
Cricothyroid membrane info
- Is it vascular?
- Where is it?
Relatively avascular
Thyroid cartilage is attached to the cricoid cartilage anteriorly by the cricothyroid membrane
Trachea location
Begins at C6 at the inferior border of the cricoid cartilage and extends to carina
Bifurcated to right and left main stem bronchus at the level of T5
How long is the trachea
10-15 cm in length and is 16-20 rings so long
At what angles do the mainstems bifurcate
Right = 25-30 degree angle Left = 45 degree angle
intrinsic muscles of the larynx job
responsible for opening, closing, and controlling tension of vocal cords
extrinsic muscles job
connect larynx with hyoid bone and other structures and serve to move the larynx as a whole (elevating and depressing) during phonation, swallowing, and breathing
what does the posterior cricoarytenoid muslce do?
abducts the vocal cords and opens the glottis
what does the lateral cricoarytenoid mucle do?
adducts the vocal cords
what do the arytenoids (muscle) do?
adducts the vocal cords
what does the criocothyroid muscle do?
produces cord tension, closure, and enlongates the vocal cords
can result in total and prodound glottic closure aka laryngospasm
what does the thyroarytenoid muscle do
shortens and relaxes the vocal cords
name the 5 intrinsic muscles of the larynx
posterior cricoarytenoid lateral cricoarytenoid arytenoid cricothyroid thryoarytenoid
which intrinsic muscle of the larynx is responsible for laryngospasm
cricothyroid
name the six extrinsic muscles of the larynx
sternohyoid sternothyroid thyrohyoid omohyoid stylohyoid mylohyoid
sternohyoid muscle function
draws hyoid bone inferiorly
depresses larynx
sternothyroid muscle function
draws thyroid cartilage caudad
Depresses larynx
thyrohyoid muscle function
draws hyoid bone inferiorly
*elevates larynx if hyoid bone is fixed
omohyoid muscle function
draws hyoid bone caudad
Depresses larynx
what is the function of the stylohoid and mylohyoid muscles?
elevate larynx
Nose sensory innervation
anterior septum and lateral walls = CNV - trigeminal nerve
*specifically the anterior ethmoidal nerve
posterior septum = CNV - trigeminal nerve
*specifically the nasopalanatine and sphenopalantine nerves
sympathetic stimulation of the nose causes
vasoconstriction and shrinkage of nasal tissue
parasympathetic stimulation of the nose causes
engorgement of blood vessels and increases likelihood of breathing with airway manipulation
seen with general anesthesia!!!
what innervates the tonsils, roof of pharynx, and underside of soft palate (sensory)?
glossopharyngeal nerve - CN 9
what innervates the anterior 2/3 of tongue (sensory)?
CNV - trigeminal
*specifically the lingual nerve/mandibular division of CNV
what innervates the posterior 1/3 of tongue? (sensory)
CN 9 - glossopharyngeal nerve
what does CN7 do? aka the facial nerve
- motor - facial expression
- sensory - taste to anterior 2/3 of tongue
- afferent conduction to oropharynx (small amount)
- motor - stylohyoid muscle (pulls hyoid bone up and back which elevates tongue)
- salivary glands - PSNS saliva production
what does CN12 do? aka hypoglossal nerve
motor - tongue muscles
what happens if you damage the hypoglossal nerve
tongue relaxes and can fall back to obstruct airway
what does CNX (vagus) nerve do?
innervates airway below epiglottis
- SUPERIOR laryngeal nerve
- sensory to larynx ABOVE cords (epiglottis to cords) = internal branch
- motor = external branch - to cricothyroid muslce
- RECURRENT laryngeal nerve
- sensory to larynx BELOW cords
- motor - all other laryngeal muscles
Which nerve provides motor innervation for all muscles of the larynx?
CNX - VAGUS
SLN external branch = motor to cricothyroid muscle
RLN = motor to all muscles of larynx EXCEPT cricothyroid
what is the superior laryngeal nerve responsible for?
INTERNAL
*sensory - larynx from epiglottis to cords aka ABOVE CORDS and lower pharynx
EXTERNAL
*motor - cricothyroid muscle of larynx
what is the recurrent laryngeal nerve responsible for?
- SENSORY - larynx BELOW CORDS and upper esophagus
- MOTOR - all muscles of larynx except cricothyroid muscle
which nerve is involved in laryngospasm
vagus X
what happens when you have injury to superior laryngeal nerve
unilateral = minimal effects bilateral = hoarseness, vocal tiring
what happens when you have injury to the recurrent laryngeal nerve
unilateral = hoarseness
bilateral
* acute - stridor, respiratory distress from unopposed tension of cricothyroid muscles
* chronic - aphonia
common after thyroidectomy because this nerve comes down and loops around inominate artery
what happens to vagus nerve injury
bilateral vagal denervatiosn produce flaccid, midpositioned cords = APHONIA
Superior laryngeal artery supplies
supraglottic laryngeal structures
flows from carotid, to superior thyroid artery, to SLA to above
inferior laryngeal artery supplies
infraglottic laryngeal structures
flows from subclavian to inferior thyroid artery to ILA to above
