Unit 1 Flashcards
“Tuning Fork” of Voice
Cricothryoid - “Cords Tense,” only intrinsic muscle innervated by SLN (external branch) .
Injury to e-SLN results in hoarseness
Chronic Injury to RLN
Is allegedly well tolerated and does not result in respiratory distress
Intrinsic Muscles vs Extrinsic Muscles of the Larynx
Intrinsic muscles of the larynx are used for phonation and vocal cord movement.
Extrinsic muscles of the larynx are used to move the larynx within the neck, allow for swallowing, breathing
Intrinsic Muscle with 2 Functions
Thyroarytenoid
- “They relax” - cords shorten
- Adducts the vocal cords - narrows the glottis
Intrinsic Muscles + Functions + Innervation (5)
Cricothyroid - “cords tense/elongate” - SLN*, “tuning fork of the void”
Vocalis - cords shorten/relax - RLN
Thyroarytenoid - cords relax/shorten, + adducts the vocal cords, narrows the glottis - RLN
Lateral Cricoayrtenoid - Adducts the vocal cords, narrows glottis - RLN
Posterior cricoayrtenoid - ABducts the vocal cords, opens the vocal cords - RLN
The vocal cords attach to
Anteriorly the vocal cords attach to the thyroid cartilage, posteriorly the vocal cords attach to the arytenoid cartilages
Sphincters of the Larynx
- Aryepiglottic Sphincter: closes laryngeal vestibule - RLN
- Interarytenoid sphincter: closes posterior commissure of the larynx - RLN
Extrinsic Muscles of the Larynx (9)
Extrinsic muscles of the larynx, elevate the larynx
- stylohyoid
- geniohyoid
- mylohyoid
- thyrohyoid
- digastric
- stylopharyngeus
Extrinsic Muscles of the larynx, depress the larynx
- omohyoid
- sternohyoid
- sternothyroid
Vagus nerve branches into SLN @
Vagus nerve branches to SLN just below the jugular foramen
SLN divides @
SLN divides into external and internal at the level of the hyoid bone, at the hyoid bone the INTERNAL pierces the thyrohyoid membrane. The external goes lower and pierces/innervates the cricothyroid muscle (“cords tense”)
Trigeminal Nerve Sensory Innervation
V1 ophthalmic - innervates the anterior ethmoidal area, nares + 1/3 of nasal septum
V2 maxillary - sphenopalatine, innervates the turbinates and rest of septum
V3 mandibular - lingual, innervates anterior 2/3 of tongue
Glossopharyngeal Nerve Innervation
Afferent (sensory) limb of gag reflex
Innervates soft palate, oropharynx, tonsils, vallecula, anterior side of epiglottis
SLN Innervation
Motor = extrinsic SLN, cricothryoid muscle. (“Cords tense”) - divides at hyoid bone, goes down to cricothyroid muscle
Sensory = Intrinsic SLN (pierces thyrohyoid membrane) innervates posterior side of epiglottis to just above cords
RLN innervation
Motor: All intrinsic muscle of larynx other than cricothyroid muscle.
Sensory: Below trachea below the levels of the vocal cords.
3 Key Airway Blocks
- Glossopharyngeal Block - blocking the afferent limb of gag reflex, soft palate, oropharynx, tonsils, vallecula, anterior side of epiglottis.
Inject at the corner of the PALATOGLOSSAL ARCH, anterior tonsillar pillar. 1-2 mL - SLN Block - blocking posterior side of epiglottis to above the cords. Inject inferior to the greater cornu of the hyoid bone on both sides. 1 mL above the thyrohyoid membrane, 2 mL below it.
- Transtracheal Block - Blocking the trachea below the glottis, inject caudally at the level of the cricothyroid membrane, tell pt to inhale, inject and then pt will laugh
Unpaired cartilages, Paired cartilages, Membranes
Unpaired Cartilages
- Epiglottis
- Thyroid
- Cricoid
Paired Cartilages
- Arytenoids
- Corniculate
- Cuneiform
Membranes:
- Thyrohyoid Membrane
- Cricothyroid Membrane
Cartilages commonly mistaken for arytenoids on laryngoscopy
Corniculate/Cuneiform
Arytenoid Cartilages articulate with cricoid cartilage!
Form a joint that can become inflamed with lupus or RA leading to airway obstruction
Laryngospasm is most common in
children <1 y/o
Sensory Innervation of Laryngospasm
Afferent (sensory) branch: internal SLN - posterior epiglottis to above the level of cords
Efferent (motor) branch: external SLN + RLN, cricothyroid (cords tends) + cords adduct (thyroarytenoid, lateral cricoarytenoid)
Risk factors for laryngospasm (9)
- child <1 y/o
- URI within the last 2 weeks
- airway manipulation in light plane of anesthesia
- Secretions/blood in oropharynx
- 2nd hand smoke!!!
- reactive airway dx
- GERD
- HYPERVENTILATION/HYPERCAPNIA
- surgical procedures involving the airway (T&A, nasal/sinus, laryngoscope, bronchoscope, palatal)
During anesthesia, upper airway can obstruct @
- Soft palate (tensor palatine muscle) - nasal pharynx
- Tongue (genioglossus muscle) - oropharynx
- Epiglottis - hyoid muscles - hypo pharynx
Trachea begins at / ends at
Trachea begins at C6, ends at T4/T5
Epithelium of the trachea
ciliated columnar epithelium
