Airway Flashcards
Posterior Cricoarytenoid
Larynx INTRINSIC
Abducts (opens) the vocal cords and opens the glottis
Lateral Cricoarytenoid
Larynx INTRINSIC
Adducts (closes) the vocal cords
Arytenoids
Larynx INTRINSIC
Adducts (closes) the vocal cords
Cricothyroid
Larynx INTRINSIC
Produces cord tension, closure, & elongates the vocal cords
Laryngospasm results in total & profound glottic closure
Thyroarytenoid
Larynx INTRINSIC
Shortens & relaxes the vocal cords
Sternohyoid
Larynx EXTRINSIC
Draws hyoid bone inferiorly
Sternothyroid
Larynx EXTRINSIC
Draws thyroid cartilage caudal
Thyrohyoid
Larynx EXTRINSIC
Connects thyroid cartilage w/ hyoid bone
Draws hyoid bone inferiorly
Internal SLN penetrate the membrane at hyoid cornu
Omohyoid
Larynx EXTRINSIC
Draws hyoid bone caudal
Stylohyoid
Larynx EXTRINSIC
Elevates the larynx
Mylohyoid
Larynx EXTRINSIC
Elevates the larynx
Trigeminal
Cranial nerve V
Lingual nerve (mandibular division)
Sensory & motor
Anterior 2/3 tongue
Facial Nerve
Cranial nerve VII Sensory & motor Taste to anterior 2/3 tongue Facial muscles - expression Motor control stylohyoid laryngeal muscle Salivary glands (PSNS stimulation)
Glossopharyngeal
Cranial nerve IX
Sensory & motor
Posterior 1/3 tongue
Vagus
Cranial nerve X
Sensory & motor
Innervates airway below the epiglottis
SLN & RLN
Hypoglossal
Cranial nerve XII
Motor below/behind the tongue
Impaired nerve or injury → airway obstruction d/t tongue relaxation
Nasopharynx
Anterior to C1
Contains nasal septum, turbinates, & adenoids
Oropharynx
C2-C3 level
Opens into mouth anteriorly
1° obstruction = tongue d/t ↓genioglossus muscle tone
Hypopharynx
Posterior to larynx
Leads to the esophagus
Superior border - epiglottis
Inferior border - cricoid cartilage
Cricoid Cartilage
COMPLETE RING
C5-C6
Narrowest portion in pediatric airway
Sellick’s maneuver (cricoid pressure) site
Waldeyer’s Tonsillar Ring
Pharyngeal tonsils (adenoids) located in nasopharynx
Palatine tonsils located in oropharynx
Lingual tonsils located at tongue base
(Tubal tonsils)
Larynx
Adults C3-C6
Infants/children C2-C4 (descends to C4-C5 by age 5)
Phonation & valve to protect lower airways
Located at junction b/w airway & esophagus
NINE Cartilages
Thyroid Cricoid Epiglottic Arytenoid (posterior pair) Corniculate (middle pair) Cuneiform (lateral pair)
Epiglottis
Broad leaf-shape
Sits at tongue base & separates hypopharynx from larynx
Covers laryngeal opening during swallowing to protect against aspiration
Vascular area → trauma & swelling
Vestibular Folds
False vocal cords
Narrow bands fibrous tissue on either side larynx
Vocal Cords
True cords
Pale, white ligamentous structures
Attach to thyroid anteriorly & arytenoids posteriorly
Glottic Opening
Narrowest portion in adult airway
Average width 6-9mm (able to stretch up to 12mm)
*Children narrowest airway portion lies just below the vocal cords at the cricoid ring
Thyroid Cartilage
Anterior neck thyroid notch
Largest larynx cartilage
Vocal cords are attached anteriorly
Cricothyroid Membrane
Relatively avascular
Attaches thyroid cartilage to the cricoid cartilage anteriorly
Emergency airway
Trachea
Begins at C6 at inferior cricoid cartilage border & extends to carina
Approximately 10-15cm
Cricoid cartilage = only complete ring
16-20 cartilagenous rings anteriorly
Bifurcates to R/L maintain bronchus at T5 level
- R bronchus 25-30° angle
- L bronchus 45°
Pediatric Airway
- Larynx positioned higher
- Tongue larger relative to mouth size
- Epiglottis large, stiffer, angled more posteriorly (omega shape)
- Head & occiput larger relative to body size
- Short neck
- Narrow nares
- Cricoid ring = narrowest region
INTRINSIC Larynx Muscles
Open, close, & control vocal cord tension
EXTRINSIC Larynx Muscles
Connect larynx w/ hyoid bone & other structures
Serve to move larynx as whole (elevating & depressing) during phonation, swallowing, & breathing
SLN
- Internal sensation SIS to larynx epiglottis to vocal cords (ABOVE)
- External motor SEM innervation to cricothyroid muscle → laryngospasm
RLN
Sensory:
- Provides sensation to larynx BELOW vocal cords & upper esophagus
Motor:
- Innervates all larynx muscles EXCEPT cricothyroid
- R leaves Vagus at subclavian level & loops UP
- L leaves Vagus at aortic arch level & loops UP
- Runs in groove alongside the trachea
Laryngeal Nerve Injury
SLN
Unilateral - minimal effects
Bilateral - hoarseness & vocal tiring
RLN Unilateral - hoarseness Bilateral - Acute → stridor & respiratory distress d/t unopposed cricothyroid muscle tension - Chronic → aphonia
Laryngeal Blood Supply
Superior laryngeal artery
- Blood supply to supraglottic laryngeal structures
- Carotid to superior thyroid artery to SLA
Inferior laryngeal artery
- Blood supply to infraglottic laryngeal structures
- Subclavian to inferior thyroid artery to ILA
Venous drainage
- Superior/inferior thyroid veins to SVC
Atlanto-Occipital Joint
“Sniffing position”
Align oral, pharyngeal, & laryngeal axes → optimal cord visualization
PiLlow aligns pharyngeal & laryngeal axes then extend to head to align the oral axis
Creates the shortest distance to intubate - straight line from incisor teeth to the glottic opening
Normal extension = 35°
Limited neck mobility <12° extension
Temporomandibular Mobility
Mouth opening or inter-incisor gap
Normal 30-40mm or 2-3 fingerbreadths
<2 fingerbreadths indicates difficult airway
3 fingerbreadths = ideal
Mallampati Sensitivity
True positive
60-80%
Mallampati Specificity
True negative
50-80%
Mallampati I
CLASS I
Hard & soft palate, tonsillar pillars, & uvula visible
Mallampati II
CLASS II
Hard & soft palate, tonsillar pillars, & partial uvula
Mallampati III
CLASS III
Hard & soft palate w/ uvula base visible
Mallampati IV
CLASS IV
Only hard palate visible
Upper Lip Bite Test
Assesses mandible mobility (protrusion)
Thyromental Distance
Patil's test Reflects amount space to displace the tongue Sniffing position w/ mouth closed Distance from thyroid cartilage notch to mentum tip Normal >6cm Retrognathia <6cm ↑risk difficult airway 6-7cm = questionable 7-8cm typically easy intubation
Considerations:
- Chin implant (assess for scar)
- Plastic surgery potential to distort anatomy
Sternomental Distance
Sniffing position w/ mouth closed
Distance between sternal notch & mentum
Normal > 13.5cm
Prayer Sign
Assesses joints & ability to align oropharyngeal & laryngeal axes
Negative - palms flat together
Positive - unable to place palms flat
Neck Circumference
> 45cm indicates difficult intubation
Average male 38cm
Literature varies 42-50cm
STOP BANG
Snoring Tired Observed apnea Pressure HTN BMI >35kg/m^2 Age >50yo Neck circumference >45cm Gender M
Cormack-Lehane I
GRADE I
Full view glottic opening & arytenoid cartilages
Cormack-Lehane II
GRADE II
Posterior portion glottic opening & arytenoid cartilage visible
Unable to visualize full vocal cords
Cormack-Lehane III
GRADE III
Only epiglottis visible
Unable to visualize glottic opening or cords
Cormack-Lehane IV
GRADE IV
Only soft palate visible
No recognizable laryngeal structures
Difficult Mask Ventilation
Beard Obesity BMI > 26kg/m^2 Neck circumference Age > 55yo Edentulous - no teeth especially upper unable to obtain/maintain proper mask seal OSA or snores
Predicting Difficult Intubation
Look externally Evaluate the mandibular space Mallampati classification Obstructions Neck mobility ROM
Sellick’s Maneuver
Cricoid Pressure
Protects against passive aspiration
Compress/occlude esophageal lumen b/w cricoid cartilage & cervical spine
RSI apply 3lbs initially when push induction drugs then ↑6.6-8.8lbs or 3-4kg
Cricoid Pressure Contraindications
Neck injury (C-collar) Esophageal rupture/tear Active emesis (opposing forces → esophageal rupture)
