Airway Anatomy Flashcards
What structures are considered the upper airway?
Nose Mouth Pharynx Hypopharynx Larynx
What are the two openings to the human airway?
The nose and the mouth
What structures are considered the lower airway?
Trachea
Bronchi
Bronchioles (terminal and respiratory)
Alveoli
What is the primary function of the nose?
Warms and humidifies gases
What structure is the primary pathway for normal breathing?
The nose, unless there is obstructions, polyps, or upper respiratory infection
What opening to the airway has more resistance?
The Nose, almost two times that of mouth breathing
What structure does the nose and mouth form?
They are separated anteriorly and joined posteriorly to form the pharynx
When does mouth breathing occur?
When high flow rates are required
What are the three compartments of the pharynx?
Nasopharynx
Oropharynx
Hypopharynx
Where is the pharynx located?
Extends from posterior aspect of nose to the level of the cricoid cartilage
What structures are present in the nasopharynx?
Nasal Septum
Turbinates/Concha
Adenoids
Where is the nasopharynx located?
Anterior to C1, bound superiorly by base of skull and inferiorly by soft palate
Where is the oropharynx located?
Lies at C2-C3, bound superiorly by soft palate and inferiorly by epiglottis
What is the major source of oropharyngeal obstructions?
The tongue due to decreased genioglossus muscle tone
Where is the hypopharynx located?
C5-C6, bound by superior border of the epiglottis and inferior border of the cricoid cartilage
What is the purpose of the upper esophageal sphincter?
Acts as a barrier to regurgitation in the conscious patient, closed when swallowing and open when breathing
What is the only complete ring of cartilage in the adult trachea?
Cricoid Cartilage
Lymphoid tissue ring in the pharynx that is at high risk for bleeding, especially with nasal intubation?
Waldeyer’s Tonsillar Ring
What makes up Waldeyer’s tonsillar ring?
Pharyngeal tonsils (adenoids)
Palatine tonsils
Lingual tonsils
Where does the larynx typically lie in infants and children?
C2-C4 and descends to C4-C5 by the age of 5
What is the purpose of the larynx?
It serves as an organ of phonation and as a valve to protect the lower airways
Where is the larynx located?
Extends from epiglottis to lower level of cricoid cartilage and sits at the junction of the airway and the esophagus
How is the trachea protected from aspiration?
The epiglottis will fold over when swallowing and the vocal cords will spasm close if irritated
How are the tracheal rings typically structured?
Incomplete posteriorly and complete anteriorly, with the exception of the cricoid cartilage
What are the components of the cartilaginous skeleton of the larynx?
Ligaments, muscles, cartilages and one bone
What is the name of the one bone included in the cartilaginous skeleton of the larynx?
Hyoid bone
Name the nine cartilages that make up the larynx?
Thyroid (one) Cricoid (one) Epiglottic (one) Corniculate (pair) Arytenoid (pair) Cuneiform (pair)
Where is the epiglottis located?
Sits at base of tongue and separates hypopharynx from the larynx and hangs over the laryngeal opening
What is important to remember about the epiglottis prior to performing DVL?
Very vascular and can be traumatized, swelling incredibly
What are the most commonly seen cartilages on laryngoscopy?
Arytenoids, pyramidal and posterior to the cords
What are the false vocal cords?
Also known as vestibular folds, narrow bands of fibrous tissue on each side of the larynx that are found first inside the laryngeal cavity opening
What do the true vocal cords looks like?
Pale, white, ligamentous structures that attach to the thyroid anteriorly and the arytenoids posteriorly
What is the narrowest portion of the adult airway?
Glottic opening
What is the average width of the glottic opening in an adults?
6-9mm but can be stretched to 12mm
What is the narrowest portion of the pediatric airway?
Just below the cords at the cricoid ring
Where should the Macintosh blade be inserted in the airway?
Valecula
What is the largest cartilage of the larynx?
Thyroid cartilage
Where is the site for Sellicks Maneuver?
Cricoid cartilage, 6.6-8.8 pounds BURP (backward, upward, rightward pressure)
Where should an emergency airway be attempted?
Cricothyroid membrane
Where is the trachea located?
Begins at C6 at the inferior border of the cricoid cartilage and extends to the carina
About how long is the trachea?
10-15cm in length
About how many cartilaginous rings compose the trachea?
16-20 rings anteriorly
When does bifurcation to right and left mainstem bronchus occur?
T5
At what angles does the right and left bronchus occur?
Right bifurcates at 25-30 degrees
Left bifurcates at 45 degrees
What mainstem is more likely to occur?
Right mainstem, fairly shallow favors intubation
What are some important considerations for the pediatric airway?
Larynx is higher Tongue large compared to size of mouth Epiglottis larger, stiffer more posterior Head large compared to body Short neck Narrow nares
What is the responsibility of the intrinsic muscles of the larynx?
Responsible for opening, closing and controlling tension of the vocal cords
What is the responsibility of the extrinsic muscles of the larynx?
Connect the larynx with the hyoid bone and other structures
Serves to move the larynx as a whole during phonation, swallowing and breathing
What is the action of the Posterior Cricoarytenoid muscle?
Abducts (opens) the vocal cords and opens the glottis
What is the action of the Lateral Cricoarytenoid muscle?
Adducts the vocal cords
What does the term Ab mean in Latin?
To move away, muscles that abduct move away and an opening can occur
What does the term Ad mean in Latin?
To move towards, muscles that adduct move together thus closing an opening
What is the action of the Arytenoid muscle?
Adducts the vocal cords
What is the action of the Cricothyroid muscle?
Produces cord tension, closure and elongates the vocal cords. Can result in total and profound glottic closure called laryngospasm
What is the action of the Thyroarytenoid muscle?
Shortens and relaxes the vocal cords
What is the action of the Sternohyoid muscle?
Draws hyoid bone inferiorly
What is the action of the Sternothyroid muscle?
Draws thyroid cartilage caudad (toward posterior end)
What is the action of the Thyrohyoid muscle?
Draws hyoid bone inferiorly
What is the action of the Omohyoid muscle?
Draws hyoid bone caudad
What is the action of the Stylohyoid muscle?
Elevated larynx
What is the action of the Mylohyoid muscle?
Elevates larynx
What nerves innervate the anterior septum and lateral walls of the nose?
Ophthalmic division of trigeminal nerve (V), specifically anterior ethmoidal nerve
What nerves innervate the posterior septum of the nose?
Maxillary division of the trigeminal nerve (V), specifically nasopalatine nerves and sphenopalatine ganglion
Why is a nose bleed more likely to occur after placing a nasal airway during general anesthesia?
SNS results in vasoconstriction, anesthesia knocks out SNS causing PSNS engorgement of blood vessels easy to damage
What cranial nerve innervates the tonsils, roof of pharynx and underside of soft palate?
Glossopharyngeal nerve (IX)
What nerves innervate the tongue?
Anterior 2/3: Lingual nerve (mandibular division f the Trigeminal nerve (V)
Posterior 1/3: Glossopharyngeal nerve (IX)
What are the functions of the facial nerve?
Muscles of facial expressions Taste Motor control of stylohyoid laryngeal muscle Salivary glands Small afferent conduction to oropharynx
Damage to which nerve may cause the tongue to relax causing it to fall back resulting in airway obstruction
Hypoglossal Nerve(XII)
Where does the vagus nerve innervate the airway?
Below the epiglottis
What are the two branches of the Superior laryngeal nerve?
Internal branch and External branch
What is the function of the internal branch of the Superior laryngeal nerve?
Provides sensation to larynx from epiglottis to vocal cords (ABOVE vocal cords)
What is the function of the external branch of the Superior laryngeal nerve?
The external branch is a motor nerve
What is the function of the Recurrent Laryngeal Nerve?
Provides sensation to larynx BELOW vocal cords
What are the names of the two branches of the Vagus nerve that innervate all muscles of the larynx?
Superior Laryngeal Nerve
Recurrent Laryngeal nerve
What is the only muscle the Recurrent Laryngeal nerve does not innervate?
Cricothyroid muscle, external branch of Superior laryngeal nerve provides motor innervation
What is the function of the Internal superior laryngeal nerve?
Sensory (SIS)
What is the function of the External superior laryngeal nerve?
Motor (SEM)
Where does the Internal superior laryngeal nerve provide sensory information?
Lower pharynx
Underside of epiglottis
Larynx above the cords
What sensory information does the recurrent laryngeal nerve provide?
Below the cords and Upper esophagus
Where does the right side of the recurrent laryngeal nerve go?
Leave vagus at the level of the subclavian and loops up
Where does the left side of the recurrent laryngeal nerve go?
Leaves vagus at the level of the aortic arch and loops up
What can occur with damage to the superior laryngeal nerve?
Unilateral: minimal effects
Bilateral: Hoarseness, vocal tiring
What can occur with damage to the recurrent laryngeal nerve?
Unilateral: Hoarseness
Bilateral:
Acute- stridor, resp distress, unopposed tension of the cricothyroid muscle
Chronic- aphonia
What is the end result if bilateral vagal denervations occurs?
Flaccid, mid-positioned cords, resulting in aphonia
What does the superior laryngeal artery supply?
Supraglottic laryngeal structures
Where does the superior laryngeal artery originate?
carotid –> superior thyroid artery –> SLA
What does the inferior laryngeal artery supply?
Infraglottic laryngeal structures
Where does the inferior laryngeal artery originate?
Subclavian –> inferior thyroid artery –> ILA
What is the venous drainage of the airway?
Superior/inferior thyroid veins to SVC
What are the five branches of the facial nerve?
Temporal Zygomatic Buccal Mandibular Cervical
What structure does the nasal airway follow?
The hard palate
What structure does the oral airway follow?
The base of the tongue
What structures does the larynx attach to?
Anteriorly by the epiglottis, posteriorly by the mucous membrane which extends between the arytenoid cartilage and laterally by the a folds
Where does the superior laryngeal nerve penetrate the throhyoid membrane?
At the level of the cornu (horn) of the hyoid
What attaches the thyroid cartilage to the cricoid cartilage?
Cricothyroid membrane (avascular)
What muscle can cause a laryngospasm?
Cricothyroid muscle (intrinsic muscle)
What structures does the Glossopharyngeal nerve innervate?
Tonsils, roof of pharynx, underside of soft palate and posterior 1/3 of tongue
What four cranial nerves innervate the tongue?
Glossopharyngeal (IX)-sensory
Trigeminal (V)-sensory
Facial (VII)-sensory
Hypoglossal (XII)-motor
What is the most important mechanism of protecting the lower airways?
Glottic closure reflex
Define the characteristics of a laryngospasm?
A prolonged, intense glottic closure and an exaggeration of glottic closure reflex
What three structures protect the lower airways from aspiration and secretions?
Pharynx
Epiglottis
Vocal cords
At what cervical structure is the carina located?
T5 (also where bronchus branches to right and left)
