Unit 1 (Respiratory) - Airway Anatomy Flashcards
____________ muscles participate in phonation and control the vocal cords (tension and position)
Intrinsic
____________ muscles support the larynx inside the neck and assist with swallowing
Extrinsic
True or false: The true vocal cords are ligaments
True
The external branch of the superior laryngeal nerve innervates what muscle?
Cricothyroid muscle
What muscles are associated with increasing/decreasing tension of the vocal ligaments?
- Cricothyroid - Elongates/tenses
- Vocalis - Shortens/relaxes
- Thyroarytenoid - Shortens/relaxes
What two muscles adduct the vocal folds, closing the glottis?
- Thyroarytenoid
- Lateral cricoarytenoid (Let’s Close Airway)
What muscle abducts the vocal folds, opening the glottis?
Posterior cricoarytenoid (Please Come Apart)
Which nerve innervates all intrinsic laryngeal muscles except the cricothyroids?
Recurrent laryngeal nerve
Which extrinsic muscles depress the larynx?
- Omohyoid
- Sternohyoid
- Sternothyroid
Which extrinsic muscles elevate the larynx?
- Digastric (Anterior and posterior belly)
- Mylohyoid
- Stylohyoid
- Thyrohyoid
During swallowing, contraction of this muscle pulls the anterior region of the cricoid cartilage towards the lower border of the thyroid cartilage, allowing it to function as an intrinsic and extrinsic muscle.
Cricothyroid muscle
What is the primary nerve that provides sensory innervation to the face and head?
Trigeminal nerve
What are the branches of the trigeminal nerve?
- V1 - Ophthalmic (Anterior ethmoidal)
- V2 - Maxillary (Sphenopalatine)
- V3 - Mandibular (Lingual)
The nares and anterior 1/3 of nasal septum are innervated by which branch of the trigeminal nerve?
V1 (Ophthalmic)
The turbinates and septum are innervated by which branch of the trigeminal nerve?
V2 (Maxillary)
The anterior 2/3 of the tongue is innervated by what branch of the trigeminal nerve?
V3 (Mandibular)
Which nerve gives sensory innervation to the oropharynx to the anterior side of the epiglottis?
Glossopharyngeal nerve (CN 9)
What is the motor function of the mandibular branch of the trigeminal nerve?
Mastication
What motor function is associated with the glossopharyngeal nerve?
Swallowing and phonation
The superior laryngeal nerve branches off of what nerve?
Vagus nerve
The right RLN loops under what structure?
Subclavian artery
The left RLN loops under what structure?
Aortic arch
Which RLN is more susceptible to injury?
The left due to its location
What is the most common nerve injury following subtotal thyroidectomy?
Unilateral RLN injury
If a patient has an acute injury of the bilateral recurrent laryngeal nerves, what symptoms would they present with?
Stridor and respiratory distress
What are the 6 topical techniques to anesthetize the upper airway?
- Cotton soaked pledgets in the nares
- Instill topical local anesthetic into each care
- Swish in swallow
- Local anesthetic spray
- Nebulization
- Atomization
If you are doing a glossopharyngeal nerve block and aspirate blood, what should you do?
Withdraw and redirect needle medially
There is a 5% chance of intracarotid injection during a glossopharyngeal nerve block which increases the risk of what?
Seizures
While doing a recurrent laryngeal nerve block, after puncturing the cricothyroid membrane, advancing the needle in what direction reduces the risk of vocal cord injury?
Caudal
What are the two anterior ligaments in the larynx?
Thyrohyoid ligament
Cricothyroid ligament
What are the unpaired cartilages in the larynx?
- Epiglottis
- Thyroid
- Cricoid
What are the paired cartilages in the larynx?
Corniculate
Arytenoid
Cuneiform
What is the only bone in the body that does not articulate with another bone?
Hyoid bone
Attaches the larynx (Specifically the thyroid cartilage) to the hyoid bone
Thyrohyoid ligament
Attaches the cricoid and thyroid cartilages
Cricothyroid ligament
Provides a mechanical barrier between the pharynx and the laryngeal opening
Epiglottis
Provides structure and protection to the larynx - Largest cartilage in the larynx
Thyroid Cartilage
Most caudal cartilage in the larynx
Only complete cartilaginous ring in the airway
Cricoid cartilage
The movement of the arytenoids can be significantly restricted by what pathologies?
Rheumatoid arthritis and systemic lupus erythematosus
In adults, what is the narrowest region of the airway?
The glottic opening
What is the narrowest fixed region in kids < 5 years old?
Cricoid ring
Narrowest dynamic region in kids < 5 years old?
Vocal cords
The sustained and involuntary contraction of the laryngeal musculature that results in the inability to ventilate
Laryngospasm
What are some complications of laryngospasm?
- Airway obstruction
- Negative pressure pulmonary edema
- Pulmonary aspiration of gastric contents
- Cardiac dysrhythmias
- Cardiac arrest
- Death
Describe the laryngospasm reflex pathway
- The internal branch of the SLN sends a message down the afferent limb to the brain 2. A motor response is elicited through the external branch of the SLN (tensing the vocal cords) and recurrent laryngeal nerve (Closing the glottis)
Signs of laryngospasm:
- Inspiratory stridor
- Suprasternal and supraclavicular retraction during inspiration
- “Rocking horse” appearance of the chest wall
- Increased diaphragmatic excursion
- Lower rib flailing
- Absent or altered EtCO2 waveform
What are some pre-anesthetic risk factors for laryngospasm?
- Active or recent URI (< 2 weeks)
- Exposure to second-hand smoke
- Reactive airway disease
- GERD
- Age < 1 year
What are some risk factors for laryngospasm that occur in the OR?
- Light anesthesia
- Saliva/blood in the upper airway
- Hyperventilation/hypocapnia
- Surgical procedures in the airway
What are interventions that reduce the risk of laryngospasm?
- Avoidance of airway manipulation during light anesthesia
- CPAP 5-10 cmH2O
- Remove pharyngeal secretions and blood before extubation
- Tracheal extubation when deeply anesthetized or fully awake
- Laryngeal lidocaine
- IV lidocaine before extubation
Treatment for laryngospasm:
- 100% Oxygen
- Remove stimulation
- Deepen anesthesia (Volatile, propofol, lidocaine)
- CPAP 15-20 cmH2O
- Succinylcholine
Where should you apply pressure if your patient is having a laryngospasm?
Larson’s Point
Exhalation against a closed glottis (or obstruction)
Example: Coughing, bucking, or bearing down
Risk: Increased pressure in the throat, abdomen, and brain
Valsalva’s maneuver
Inhalation against a closed glottis (or obstruction)
Example: Patient bites down on ETT and takes deep breath
Risk: Negative pressure pulmonary edema
Muller’s maneuver
Airway resistance through the nasal passage is ____ the resistance through the mouth?
2x
The primary functions of the upper airway include:
- Warming and humidifying inspired air
- Filtering particulate matter
- Preventing aspiration
When the patient is intubated, what takes the place of the upper airway and warms/humidifies the inspired air?
HME (Heat and moisture exchanger)
In the awake state, the upper airway is held open by three sets of dilator muscles. What are the muscles?
- Tensor palatine (Opens the nasopharynx)
- Genioglossus (Opens the oropharynx)
- Hyoid muscles (Opens the hypopharynx)
Conditions that reduce the diameter of the pharynx
- Reduced pharyngeal dilator muscle tone
- Negative pressure during inspiration
Conditions that reduce the size of the “box” (head and neck tissue:
- Increased soft tissue inside the box (Obesity, large tongue, tonsil/adenoid hypertrophy)
- Decreased size of the box (Small craniofacial structures, craniofacial deformity)
Where are the most likely locations of obstruction due to anesthesia?
- At the level of the tongue
- At the level of the soft palate
The trachea begins at _____ and ends at _______
- C6
- T4-5 at the carina
The right bronchus is _______ in length and projects about ______ degrees from the long axis of the trachea
- 2.5 cm
- 25 degrees
The left bronchus is _____ cm in length and takes off at approximately _____ degrees
- 5 cm
- 45 degrees
Which cells provide surface for gas exchange, are flat squamous cells, cover 80% of alveolar surface, and form tight junctions
Type I cells
Which cells produce surfactant, are resistant to oxygen toxicity, are capable of cell division, and can produce type I cells
Type II Cells
Which cells are macrophages, fight lung infection, and produce inflammatory response
Type III Cells
These cells are present in the alveoli in smokers and patients with acute lung injury
Nuetrophils
What 2 landmarks correspond with the carina?
T4-5 and Angle of Louis
What structures permit air movement between alveoli?
Pores of Kohn
Contraction of which muscles widens the glottic aperture?
Posterior cricoarytenoid
Which structures are anesthetized by injecting lidocaine at the base of the palatoglossal arch?
Vallecula
Oropharynx
Calculate the dose of IM Succinylcholine for a 12 kg patient?
48 mg
(12 kg x 4 mg/kg = 48 mg)
A patient bites down on the endotracheal tube during anesthetic emergence. Pink frothy sputum is noted inside the breathing circuit. Which maneuver explains the pathophysiology of this complication?
Muller’s
