Lower AirwayLower Airway

Larynx Tracheobronchial Tree (TB Tree)

Trachea Bronchi Bronchioles

Respiratory Terminal

Hyoid BoneHyoid Bone

Not part of the larynx. The Hyoid bone is an

anchor for the anterior muscles of the neck and is highly mobile. It also attaches to the muscles of the tongue to provide a stable or mobile base as the mobility of the tongue requires.

LarynxLarynx

Voice Box Function

Prevents aspiration Generates sound for speech Conducts air between the pharynx and

trachea Creates pressure changes

AspirationAspiration

Aspiration is the movement of food, liquid, vomit or a foreign substance into the trachea.

Aspiration usually involves coughing or choking until the substance is removed if the patient has intact reflexes

If large amounts of material or acidic, caustic materials (vomit) are aspirated, lung damage will result

Increased Risk of Aspiration

•Extremes of Age

•Recent Meal

•Delayed gastric emptying

•Trauma

•Depressed level of consciousness

•Poor motor control

Cartilages of the LarynxCartilages of the Larynx

Composed of nine cartilages

Three unpaired cartilage Thyroid (Greek for Oblong Shield) Cricoid (Greek for ring) Epiglottitis (Greek for “above glottis”)

Three paired cartilages (six total) Arytenoids (Greek for ladle) Corniculates (Latin for horns – cornucopia) Cuneiforms (Latin for wedge)

2. Arytenoid cartilage

3. Cervical trachea

6. Epiglottic larynx

7. Epiglottis

8. False Vocal Cords

9. Hyoid Bone

12. Subglottic larynx

15. True Vocal Cords

Paired CartilagesPaired Cartilages

The Arytenoids, Cuneiforms, and Corniculates are all associated with movement of the vocal cords and are used in phonation.

Thyroid CartilageThyroid Cartilage The largest laryngeal cartilage

is the thyroid cartilage “Adam’s Apple”

Superior border has a V-shaped notch.

Suspended from hyoid bone. Posterior wall is open. The true and false vocal cords

are found on the interior of the larynx.

Vocal CordsVocal Cords Two pairs of folds that protrude inward:

Upper pair – False cords Lower pair – True cords

The space between the vocal cords is called the rima glottidis or glottis Narrowest portion of the adult airway

Vocal CordsVocal Cords

Vocal CordsVocal Cords Vocal Cord Abduction

Cords are opening or moving away from the midline

This occurs during inspiration Vocal Cord Adduction

Cords are moving toward the midline or coming together

This occurs during expiration http://www.entusa.com/normal_larynx.htm

EpiglottisEpiglottis

Spoon-shaped cartilage which prevents aspiration by covering the opening of the larynx during swallowing.

The tongue and the epiglottis are connected by folds of mucous membranes which form a small space called the vallecula.

IntubationIntubation A device called a laryngoscope is used to

visualize the laryngeal structures. It is composed of a handle and one of two

types of blades: A curved blade (McIntosh) A straight blade (Miller or Wisconsin)

A straight laryngoscope blade is used to directlydirectly lift the epiglottis during intubation

A curved laryngoscope blade is inserted into the vallecula during intubation to lift the epiglottis indirectlyindirectly.

Cricoid CartilageCricoid Cartilage

Resembles signet (class) ring.

Inferior to Thyroid. Only complete ring of

laryngeal structures. Inferior border is attached

to the first C-shaped tracheal ring.

The narrowest portion of the airway in an infant. We use this fact when

ventilating infants as infant ET tubes do not have cuffs to seal the trachea.

Cricothyroid membraneCricothyroid membrane

Connects the cricoid and thyroid cartilages

Is the site for an emergency airway Cricothyrotomy

Laryngeal SwellingLaryngeal Swelling

Swelling (edema) at the glottis, subglottic or supraglottic region can cause stridor

Stridor is a high pitched crowing sound usually heard on inspiration from air traveling through a narrowed opening Croup, Epiglottis, Foreign Body

http://www.rale.ca/Stridor.htm

LaryngospasmLaryngospasm

A laryngeal reflex which will close the vocal cords inside the larynx

Laryngospasm results from Extubations Near drowning Inhalation of noxious substances Smoke inhalation

Valsalva ManeuverValsalva Maneuver

Forced expiratory effort against a closed glottis to increase intrathoracic pressure (defecation) or to inflate the eustachian tubes and middle ears (“clearing” of the ears on airplanes).

The larynx will tightly seal preventing air from escaping during physical work Lifting, pushing, throat-clearing, vomiting,

urination, defecation and parturition.

Head Head PositionPosition

FlexedFlexed

ExtendedExtended

Histology of the LarynxHistology of the Larynx

Above the vocal cords stratified squamous epithelium

Below the vocal cords pseudostratified columnar epithelium

Trachea to respiratory bronchioles

Tracheobronchial TreeTracheobronchial Tree Two Divisions

Cartilaginous Airways Primarily conducting airways; no gas exchange.

Noncartilaginous Airways Both conducting airways and sites of gas exchange.

Dichotomous Branching Each airway divides into two “daughter” branches Each division (bifurcation) gives rise to a new

generation of airways As airways divide, they become

Shorter Narrower More numerous

Cartilaginous AirwaysCartilaginous Airways

Trachea Main Stem Bronchi Lobar Bronchi Segmental Bronchi Subsegmental Bronchi

Lobar Bronchi

TracheaTrachea

Generation 0 11 – 13 cm long and 1.5 – 2.5 cm wide. Extends from Cricoid cartilage (6th cervical

vertebrae) to the 2nd costal cartilage or 5th thoracic vertebrae. C6 – T5

15 - 20 C-shaped cartilages supports the trachea.

Posterior wall is contiguous with esophagus.

TracheaTrachea The end of the trachea is called the carina.

This is the division of the trachea into the right and left mainstem bronchi.

Air is 100% saturated with water vapor and is warmed to 37 °C (body temperature).

The carina is located at approximately T5 or the Angle of Louis.

The surgical opening into the trachea is called a tracheostomy. 2nd or 3rd tracheal ring.

Main Stem BronchiMain Stem Bronchi

Generation 1 Trachea divides into the right and left mainstem

bronchi – one for each lung Right Mainstem is wider, shorter and more

vertical Branches at a 25 degree angle

Left Mainstem Branches at a 40 – 60 angle

Infants Both mainstem bronchi form a 55 angle with the

trachea

Newborn

Complications of IntubationComplications of Intubation

During intubations, if the tube is advanced to far, the tube will usually go into the right mainstem bronchi. Lung inflation will be absent on the left but present

on the right. Withdraw tube until bilateral sounds are heard.

Failure to hear lung sounds or visualize chest inflation on either side means the tube is probably in the stomach. Extubate the patient and re-attempt the intubation.

AspirationAspiration

Children who aspirate objects Foreign body usually lodged in right main

stem bronchi secondary to the angle being less acute.

Wheezing on right or absent lung sounds (breath sounds).

Lobar BronchiLobar Bronchi

Generation 2 Lobar Bronchi correlate to the number of

lobes of the lung. The right mainstem bronchi will divide into the

right upper, right middle and right lower lobe bronchi.

The left mainstem bronchi will divide into the left upper and left lower lobe bronchi.

Segmental BronchiSegmental Bronchi

Generation 3 Correlate with the segments of the lung. There are 10 segmental bronchi on the

right. There are 8 segmental bronchi on the

left.

Subsegmental BronchiSubsegmental Bronchi

4th to 9th Generations 1 to 4 mm in diameter Connective tissue containing:

Nerves Lymphatics Bronchial Arteries

Non-Cartilaginous AirwaysNon-Cartilaginous Airways Bronchioles

10th to 15th Generation. 1 mm in diameter. Simple cuboidal epithelium. No cartilage.

Terminal Bronchioles Less than 0.5 mm in diameter. No cartilage (lack of support). Cilia and mucous glands

disappear. Clara Cells appear Inter-bronchiole connections

called Canals of Lambert begin to appear.

Blood Supply to the Blood Supply to the Tracheobronchial TreeTracheobronchial Tree

Bronchial Blood Supply Bronchial arteries nourish the tracheobronchial tree The arteries arise from the aorta and follow the

tracheobronchial tree as far as the terminal bronchioles. Beyond the terminal bronchioles pulmonary arteries &

capillaries feed the airways & alveoli.

Normal bronchial blood flow is approximately 1% of the cardiac output.

Also feed the mediastinal lymph nodes, pulmonary nerves, part of the esophagus and the visceral pleura.

Review of TB TreeReview of TB Tree

Trachea Mainstm Bronchi Lobar Bronchi Segmental Bronchi Subsegmental Bronchi Bronchioles – cartilage disappears Terminal Bronchioles

Site of Gas ExchangeSite of Gas Exchange“The Respiratory Zone”“The Respiratory Zone”

Consists of the respiratory bronchioles, alveolar ducts, and alveolar sacs, and alveoli.

Parenchyma, Acinus or Primary Lobule.

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Attribution

Alveolar EpitheliumAlveolar Epithelium Two principal cell types:

Alveolar Type I Cells Squamous pneumocyte Broad thin cells. 95% of alveolar surface 0.1 to 0.5 thick

Alveolar Type II Cells 5% of alveolar surface Cuboidal in shape Responsible for secretion of pulmonary surfactant

that reduce surface tension and keep the alveoli stable.

Facts about the LungsFacts about the Lungs

There are 300 million alveoli in the lungs.

The surface area of the lungs is 75-85 square meters (Tennis Court).

The lung has 35 times more surface area then the skin.

Additional Components of Additional Components of Alveolar EpitheliumAlveolar Epithelium

Pores of Kohn Small holes in the walls of

interalveolar septa. 3 to 13 in diameter

Alveolar Macrophages or Type III alveolar cells. Major role in removing

bacteria and other foreign particles.

Interstitium Gel-like substance between

alveoli-capillary clusters that add support

LungLung Extends from the diaphragm to 1-2 cm

above the clavicles (about the 1st rib). The lung apex is at the top of the lung and

is somewhat pointed. The base is broad and concave and lies

at about the 6th rib or xiphoid process anteriorly, the 8th rib laterally, and the 11th rib posteriorly.

The right lung is larger and heavier than the left.

Lung Lobes and SegmentsLung Lobes and Segments

Right lung Three Lobes

Upper, Middle, Lower Divided by the Horizontal and Oblique fissures.

10 Segments

Left lung Two Lobes

Upper and Lower Divided by the Oblique fissures.

8 Segments

LOBES AND SEGMENTS OF THE LUNGS 

RIGHT LUNG LEFT LUNG

UPPER LOBE UPPER LOBE (UPPER DIVISION)

• APICAL SEGMENT ANTERIOR SEGMENT

• POSTERIOR SEGMENT

•APICAL/POSTERIOR •ANTERIOR

MIDDLE LOBE UPPER LOBE (LINGULA)

•LATERAL •MEDIAL

•SUPERIOR •INFERIOR

LOWER LOBE LOWER LOBE

•SUPERIOR•ANTERIOR BASAL•MEDIAL BASAL•LATERAL BASAL•POSTERIOR BASAL

•SUPERIOR•ANTERIOR/MEDIAL BASAL •LATERAL BASAL•POSTERIOR BASAL

Lung FissuresLung Fissures

Oblique Fissure Found in the left and right lung Separates the upper and lower lobes of

both lungs Horizontal or minor Fissure

Found only in the right lung Separates the upper and middle lobes

Horizontal fissure

Oblique fissure

HilumHilum

The hilum is where arteries, veins, bronchi, nerves and lymph vessels enter and leave the lung.

It is located on the medial border of the lung.