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ANATOMY OF LARYNX &
TRACHEOBRONCHIAL
TREE AND CONTROL OF
BREATHING
-Dr Ashish Pareek
1st year residentDept of Anaesthesiology
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Respiratory System
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Lower Airway
Larynx
Tracheobronchial Tree (TB Tree)
Trachea
Bronchi
Bronchioles
Respiratory
Terminal
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Larynx
Voice Box
Function
Prevents aspiration
Generates sound for speech
Conducts air between the pharynx andtrachea
Creates pressure changes
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Cartilages of the Larynx
Composed of nine cartilagesThree unpaired cartilage
Thyroid
Cricoid Epiglottitis
Three paired cartilages (six total)
Arytenoid
Corniculates
Cuneiforms
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Thyroid Cartilage
The largest laryngeal cartilage is thethyroid cartilage
Adams 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.
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Cricoid 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 aninfant.
We use this fact when ventilating infantsas infant ET tubes do not have cuffs toseal the trachea.
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Epiglottis
Spoon-shaped cartilagewhich preventsaspiration by covering
the opening of thelarynx duringswallowing.
The tongue and the
epiglottis are connectedby folds of mucousmembranes which forma small space called the
vallecula.
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Paired Cartilages
The Arytenoids, Cuneiforms, and Corniculatesare all associated with movement of the vocal
cords and are used in phonation.
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Vocal 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
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Vocal Cords
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Vocal Cords
Vocal Cord AbductionCords 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
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Histology of the Larynx
Above the vocal cords
stratified squamous epithelium
Below the vocal cordspseudostratified columnar
epithelium
Trachea to respiratory bronchioles
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Muscles of larynx
Cricothyroid
Posterior cricoarytenoid
Lateral cricoarytenoid
Transverse arytenoid Oblique arytenoid
Aryepiglotticus
Thyroarytenoid
Thyroepiglotticus
Vocalis
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Nerve supply of larynx
Motor nerves
All the muscles of larynx are supplied by the
recurrent laryngeal nerve except cricothyroidwhich is supplied by external laryngeal nerve
Sensory nerves
Internal laryngeal nerve- upto level of vocal foldReccurent laryngeal nerve- below vocal fold
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Blood supply & lymphatic drainage of
larynx
Upto vocal folds - sup laryngeal artery & vein
- anterosuperior group of
deep cervical lymph nodes
Below vocal fold - inf laryngeal artery & vein
- posteroinferior group of
deep cervical lymph nodes
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Applied anatomy
Laryngospasm
A laryngeal reflex which will close thevocal cords inside the larynx
Laryngospasm results from
Extubations
Near drowning
Inhalation of noxious substances
Smoke inhalation
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Tracheobronchial Tree
Two DivisionsCartilaginous Airways
Primarily conducting airways; no gasexchange.
Trachea to terminal bronchioles which isciliated for removal of debris, mucuslined
Noncartilaginous Airways Both conducting airways and sites of gas
exchange.
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Cartilaginous Airways
Trachea
Main Stem Bronchi
Lobar Bronchi
Segmental Bronchi
Subsegmental Bronchi
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Lobar Bronchi
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Trachea
Generation 0
11 13 cm long and 1.5 2.5 cmwide.
Extends from Cricoid cartilage (6
th
cervical vertebrae) to the 2nd costalcartilage (5th thoracic vertebrae).
15 -2
0 C-shaped cartilages supportsthe trachea.
Posterior wall is contiguous withesophagus.
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The end of the trachea is called thecarina.
This is the division of the trachea intothe right and left mainstem bronchi.
The carina is located at approximatelyT5 or the Angle ofLouis.
The surgical opening into the trachea iscalled a tracheostomy.
2nd or 3rd tracheal ring.
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Main Stem Bronchi Generation 1
Trachea divides into the right and leftmainstem bronchi one for each lung
Right Mainstem is wider, shorter and
more verticalBranches at a 25 degree angle
LeftMainstem
Branches at a 40 60 angle Infants
Both mainstem bronchi form a 55
angle with the trachea
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Newborn
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Applied-Complications of Intubation
During intubations, if the tube is advanced tofar, the tube will usually go into the rightmainstem 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 chestinflation on either side means the tube isprobably in the stomach.
Extubate the patient and re-attempt the
intubation.
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Aspiration
Children who aspirate objects
Foreign body usually lodged in right
main stem bronchi secondary to theangle being less acute.
Wheezing on right or absent lung
sounds (breath sounds).
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Lobar 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.
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Segmental Bronchi
Generation 3
Correlate with the segments of the lung.
There are 10 segmental bronchi on theright.
There are 8 segmental bronchi on the
left.
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Subsegmental Bronchi
4th to 9th Generations
1 to 4 mm in diameter
Connective tissue containing:Nerves
Lymphatics
Bronchial Arteries
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Non-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
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Blood Supply Bronchial Blood Supply
--Bronchial arteries nourish thetracheobronchial tree
--The arteries arise from the aorta and follow
the tracheobronchial tree as far as theterminal bronchioles.
--Beyond the terminal bronchioles pulmonary
arteries & capillaries feed the airways &alveoli.
--Normal bronchial blood flow is approximately
1% of the cardiac output.
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Respiratory Areas in Brainstem
Medullary respiratory center
Dorsal groups stimulate the diaphragm
Ventral groups stimulate the intercostaland abdominal muscles
Pontine (pneumotaxic) respiratory group
Involved with switching between
inspiration and expiration
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Respiratory Structures in Brainstem
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Rhythmic Ventilation
Starting inspiration Medullary respiratory center neurons are continuously active
Center receives stimulation from receptors and simulation from parts ofbrain concerned with voluntary respiratory movements and emotion
Combined input from all sources causes action potentials to stimulate
respiratory muscles
Increasing inspiration More and more neurons are activated
Stopping inspiration
Neurons stimulating also responsible for stopping inspiration andreceive input from pontine group and stretch receptors in lungs.Inhibitory neurons activated and relaxation of respiratory musclesresults in expiration.
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Modification of Ventilation
Cerebral and limbic
system
Respiration can bevoluntarily controlled
and modified by
emotions
Chemical control
Carbon dioxide is major
regulator
Increase or decrease in
pH can stimulate chemo-
sensitive area, causing a
greater rate and depth of
respiration
Oxygen levels in blood
affect respiration when a
50% or greater decrease
from normal levels exists
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Modifying Respiration
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Regulation of Blood pH and Gases
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Herring-Breuer Reflex
Limits the degree of inspiration and prevents
overinflation of the lungs
Infants
Reflex plays a role in regulating basic rhythm of
breathing and preventing overinflation of lungs
Adults
R
eflex important only when tidal volume large as inexercise
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Ventilation in Exercise
Ventilation increases abruptly At onset of exercise
Movement of limbs has strong influence
Learned component
Ventilation increases gradually
After immediate increase, gradual increaseoccurs (4-6 minutes)
Anaerobic threshold is highest level of exercisewithout causing significant change in blood pH
If exceeded, lactic acid produced by skeletal muscles
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Effects of Aging
Vital capacity and maximum minute
ventilation decrease
Residual volume and dead space increase
Ability to remove mucus from respiratory
passageways decreases
Gas exchange across respiratory membrane
is reduced