Principles of Airway lecture 1

What are the two primary pathways for air into the body?

Nasal Pathway and Oral Pathway

What are the main functions of the nasal pathway?

"Rain On Hot Fields Produces Steam"

Respiration, Olfaction, Humidification, Filtration, Phonation, and serving as a reservoir for secretions.

What divides the nasal cavity into right and left sides?

The nasal septum

What are the anterior nares?

The two openings in the inferior portion of the nose.

What are choanae?

The openings at the posterior portions of the nares that lead into the nasopharynx.

What is choanal atresia?

A condition where infants are born without either nasal opening, requiring urgent surgical correction.

What structures make up the nasal septum?

Perpendicular plates of the ethmoid and vomer bones, and the septal cartilage.

The ethmoid bone descends from the cribriform plate and communicates with the anterior fossa of the cranium

What are the conchae or turbinates?

Three bony projections in the lateral wall of the nasal cavity that increase surface area for warming and humidifying air.

What are the four meatuses in the nasal cavity?

Inferior, middle, superior, and spheno-ethmoid meatus.

What are the two parts of the oral cavity?

Vestibule and Oral Cavity Proper.

What is the function of the uvula?

It helps in the swallowing process and prevents food from entering the nasal cavity.

What is Waldeyer's Ring?

A ring of lymphoid tissue that includes the adenoid tonsil, tubal tonsils, palatine tonsils, and lingual tonsil.

What is the primary function of the tongue?

Used for speech, taste, deglutition (swallowing), and oral cleansing.

Sensory fibers for the posterior 1/3 of the tongue come from the

glossopharyngeal nerve (CN IX)

Taste is achieved by the

chorda tympani branch of the nervus intermedius (from facial nerve CN VII)

Sensory fibers for the anterior 2/3 of the tongue

provided by the lingual nerve (part of trigeminal nerve CN V).

What is the primary cause of airway obstruction in unconscious patients?

The tongue displacing posteriorly and occluding the airway.

What are the three parts of the pharynx?

Nasopharynx, Oropharynx, and Laryngopharynx.

What is the function of the larynx?

To guard the entrance into the trachea and produce sound.

What are the three single cartilages of the larynx?

Epiglottis, Thyroid, and Cricoid cartilages.

What is the role of the epiglottis during swallowing?

It prevents food from entering the larynx by moving downward.

What can occur if the epiglottis becomes acutely inflamed?

Life-threatening airway obstruction may occur.

What is the anatomical location of the larynx?

Between the C3 and C6 vertebrae in adults.

What is the widest part of the pharynx?

The hyoid bone.

What is the narrowest part of the pharynx?

The level where it joins the esophagus.

What is the prominent notch formed by the thyroid cartilage in men called?

Adam's apple

What is the shape of the cricoid cartilage?

Shaped like a signet ring

What is the purpose of cricoid pressure during anesthesia induction?

To prevent passive regurgitation of gastric contents

What is the name of the maneuver used to apply cricoid pressure?

Sellick's maneuver

What is an emergency cricothyrotomy used for?

To relieve acute airway obstruction

What type of cartilage are the arytenoids made of?

Hyaline cartilage

What is the function of the arytenoids in the larynx?

They control vocal cord movement and speech

What type of cartilage are the cuneiforms made of?

Elastic cartilage

What is the nerve supply to the larynx primarily derived from?

Two branches of the vagus nerve: the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN)

Which muscle does the external branch of the superior laryngeal nerve supply?

Cricothyroid muscle

What is the role of the intrinsic muscles of the larynx?

To adjust tension in vocal ligaments and control vocal cord movement

What are the actions of the cricothyroid muscles?

Forward tilting of the thyroid cartilage, lengthening, and increasing tension on the vocal cords

What happens during quiet respiration in the larynx?

Both rimas are open, and the rima glottis is triangular

What is the position of the vocal cords during phonation?

Midline (median position)

What are the symptoms of superior laryngeal nerve (SLN) damage?

Hoarseness, wavy vocal cords, frequent throat clearing, inability to increase pitch

What is the emergency condition caused by bilateral abductor palsy of the recurrent laryngeal nerve (RLN)?

Both sides will not open, requiring immediate intervention

What is laryngeal spasm?

A protective involuntary reflex closure of the glottis

What is the trachea's structure?

A fibro-cartilaginous tubular structure with 18-24 c-shaped cartilages

What is the typical length of the trachea in adults?

Between 10 and 15 cm

Where does the trachea bifurcate?

At about the level of the fifth thoracic vertebra

Which bronchus is more likely to receive aspirated objects?

Right upper lobe bronchus

What is the angle of the left main stem bronchus as it exits the trachea?

About 40°