A detailed description on anatomy of respiratory system.

1. Anatomy of Respiratory
System
Dr. Anand Kumar Bansal
Junior Resident
Department Of Pulmonary Medicine
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2. Functional Anatomy of the
Respiratory System
Upper respiratory tract
– Nose, nasal cavity, and paranasal sinuses
– Pharynx and larynx
Lower respiratory tract
– Trachea
– Bronchi and smaller bronchioles
– Lungs and alveoli
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3. Nose
FUNTIONS --
• Provides an airway for respiration
• Moistens and warms air
• Filters inhaled air
• Resonating chamber for speech
• Houses olfactory receptors
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4. NOSE
• External nares – nostrils
• Nasal cavity divided by – nasal septum
• Posterior nasal apertures-choanae
continous with nasopharynx.
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5. Nasal Conchae
• Superior and middle nasal conchae
– Part of the ethmoid bone
• Inferior nasal conchae
– Separate bone
• Project medially from the lateral wall of the nasal
cavity
• Create streamline flow of air and provide larger
surface area for humidification of air
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6. • Two types of mucous membrane
– Olfactory mucosa
 Near roof of nasal cavity
 Houses olfactory (smell) receptors
– Respiratory mucosa
 Lines nasal cavity
 Epithelium is pseudostratified ciliated columnar
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7. Blood supply of Nose
• Lateral nasal wall is supplied by the
sphenopalatine artery posteroinferiorly and
by the anterior and posterior ethmoid arteries
superiorly.
• The nasal septum also derives its blood
supply from the sphenopalatine and the
anterior and posterior ethmoid arteries with
the added contribution of the superior labial
artery (anteriorly) and the greater palatine
artery (posteriorly)
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8. The Paranasal Sinuses
• Air containing cavities in certain bones of skull.
• Lined with mucous membrane continuous with that of
nasal cavity.
• Communicate with nasal fossa through their various ostia.
Functions -
• May have a role in air-conditioning of the inspired air.
• May reduce weight of the skull or simply act as protector
to eyes in trauma.
• May give resonance to voice.
• May thermally insulate skull base and orbit.
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9. The nasal sinuses are eight in number, four on
each side of the nose.
• Right and Left Frontal sinuses
• Right and Left Ethmoidal sinuses
• Right and Left Maxillary sinuses
• Right and Left Sphenoidal sinuses
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10. Clinically , paranasal sinuses are
divided into 2 groups-
The Anterior Group draining below the middle turbinate
or near the infundibulum consists of:
• Frontal
• Maxillary
• Anterior and Middle Group of Ethmoidal cells
The Posterior Group draining at several locations above
the middle turbinate is made up of:
• Posterior Ethmoidal Cells
• Sphenoidal Sinuses
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11. The Pharynx
• Pharynx is a conical fibromuscular tube forming
the upper part of air and food passages.
• 12-14cm long
• Divided into three sections by location
– Nasopharynx
– Oropharynx
– Laryngopharynx
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12. Division of Pharynx
• a)Base of skull (basiocciput and
basisphenoid) soft palate
• b)Plane of hard palate hyoid
bone
• c) Hyoid bone lower border
of cricoid cartilage
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13. Nasopharynx
• Only an air passageway
• Closed off during swallowing
• Contains the opening to the pharyngotympanic tube
(Eustachian or auditory tube)
• Nasopharyngeal tonsil (adenoids)
– Located on posterior wall
– Destroys entering pathogens
• Tubal tonsil
• Provides some protection from infection
• Epithelium
– Pseudostratified Ciliated columnar epithelium
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14. Oropharynx
• Lies opposite to the oral cavity with which it
communicates through oropharyngeal isthmus.
OROPHARYNGEAL ISTHMUS-boundaries.
• Soft palate above.
• Upper surface of tongue below.
• Palatoglossal arch on either sides.
Two types of tonsils in the oropharynx
– Palatine tonsils – in the lateral walls of the fauces
– Lingual tonsils – covers the posterior surface of the tongue
• Epithelium
– Stratified squamous epithelium
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15. Laryngopharynx(Hypopharynx)
• Passageway for both food and air
• Lowest part of pharynx
Boundaries
• Above oropharynx
• Below oesophagus
• Ant laryngeal cavity or inlet
• Epithelium
– Lined by Stratified squamous epithelium
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16. 16

17. Waldeyer’s Ring
• A ring composed of
MALT at beginning
of food and air
passage.
• Produce B and T
lymphocytes
• Local defense
• Also produce
lymphocytes to send
to other lymph
nodes.
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18. The Larynx
 It lies anterior to the hypopharynx
Opposite to C3- C6 vertebrae
Three functions
– Provides an open airway and Protection of the lower
airways
– Voice production
– Respiration
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19. • Larynx is formed by Nine Cartilages
• Three unpaired cartilages
– Thyroid cartilage
– Epiglottis
– Cricoid cartilage
• Three pairs of small cartilages
Arytenoid cartilages
Corniculate cartilages
Cuneiform cartilages
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20. Vocal ligaments of the larynx
– Vocal folds (true vocal cords)
 Act in sound production
– Vestibular folds (false vocal cords)
 No role in sound production
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21. Subdivisions
Vertically, the larynx is
divided into 3 regions:
• Supraglottis – Includes the
epiglottis, aryepiglottic folds,
false vocal folds, arytenoids,
and ventricle
• Glottis – true vocal folds,
anterior commissure and
posterior commissure
• Subglottis – below the true
vocal folds to the inferior
border of the cricoid cartilage
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22. Mucosa
• Mucosa of glottic and Supragottic regions is stratified
squamous epithelium.
• Mucosa of ventricles and sub-glottic regions is
pseudo-stratified ciliated epithelium
• Supra and sub glottic regions particularly ventricles
are rich in submucosal mucous or minor salivary
glands while glottis is not.
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23. Muscles of Larynx
• Extrinsic musculature – connects the larynx to
the sternum, tongue, pharynx and hyoid
apparatus.
• Intrinsic musculature - connects the laryngeal
cartilages
Cricothyroid muscle
Posterior cricoarytenoid muscle
Lateral cricoarytenoid muscle
Thyroarytenoid muscle
Transverse arytenoid muscle
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24. Anatomy of larynx
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25. Cricothyroid Muscle
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26. Adductors of the Vocal Folds
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27. Abductor of Larynx
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28. Nerve supply : Derived from the Vagus
Superior laryngeal nerve
• Supplies cricothyroid muscle
• Sensory supply to larynx above vocal cords
Recurrent laryngeal nerve
• Supplies all intrinsic muscles except cricothyroid
• Sensory supply to larynx below vocal cords
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29. ARTERIAL SUPPLY
• Sup. Laryngeal artery which originates from
Sup. Thyroid artery branch of External carotid
artery
• Inf. Laryngeal artery which originates from Inf.
Thyroid artery branch of Thyrocervical trunk
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30. The Trachea
• Is a tube which descends into the
mediastinum.
• It is kept open by 15-20 C-shaped cartilage rings
which are incomplete posteriorly.
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31. • It is 10-12cm in length extending from lower part of larynx.
• It starts at the level of 6th cervical vertebra and ends near
carina where it divides into left and right main bronchus.
• The most inferior tracheal cartilage separates the primary
bronchi at their origin and forms an internal ridge called
the carina. It correspondes to the level of 5th thoracic
vertebra.
• The trachea moves up with respiration and with alterations
with the position of the head.
• In deep inspiration the carina can descend as much as 2.5cm.
• In the child the trachea is smaller, more deeply placed, and
more movable than in the adult.
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32. 32
Trachea
Right and Left Principal Bronchus
Lobar Bronchi(Secondary)[2L,3R]
Segmental Bronchi(Tertiary)[8L,10R]
Terminal Bronchioles(25000 in no.)
Respiratory Bronchioles
Alveolar ducts
ACINUS
Alveolar sacs
Alveoli

33. BRONCHI
The trachea divides at the carina into right
and left main bronchus.
RIGHT MAIN BRONCHUS
• It is 2.5cm long
• It is wider, shorter and more vertical in direction than the left
bronchus.
• In children under the age of 3 years the angulation of two
main bronchus at carina are equal on both sides.
• In adults the right main bronchus is angulated at 25˚and the
left main bronchus is angulated at 45˚from midline.
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34. • The azygos vein arches over it from behind and
the right pulmonary artery lies at first below and
then in front of it.
• The right main bronchus divides into three lobar
bronchi to supply respective lobes.
• Right main bronchus is the commonest site for
aspiration .
• If a patient in right lateral position aspirates, the
material gravitates into lateral portion of
posterior segment of upper lobe.
• If patient aspirates in supine position, the
material gravitates to apical segment of lower
lobe.
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35. LEFT MAIN BRONCHUS
• It is narrower than the right bronchus and is
nearly 5cm long.
• The left main bronchus divides into two lobar
bronchi for upper and middle lobes.
• It passes beneath the aortic arch, crosses in
front of the esophagus, the thoracic duct, and
the descending aorta, and has the left
pulmonary artery lying at first above, and then
in front of it
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36. Bronchioles
• The bronchi divide dichotomously into several
million terminal bronchioles to terminate in
one or more respiratory bronchioles.
• Bronchioles are less than 1 mm in diameter.
• The cartilagenous rings that are seen in
bronchioles are replaced by cartilagenous
plates as the size of bronchioles decrease.
• The cartilage completely disappear when their
size reaches to 0.6mm.
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37. • The small terminal bronchioles are supported
by smooth muscle cells.
• Distal to each terminal bronchiole is an
acinus, which consists of three to four orders
of respiratory bronchioles.
• Respiratory bronchioles lead to alveolar
ducts. The walls of these ducts consist of
alveolar sacs or the mouths of alveoli.
• Smooth muscles are found in the walls of the
airways upto the level of alveolar ducts.
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38. Terminal bronchiole
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B Feng and Q Song

39. Structures of the Respiratory Zone
 ALVEOLI
 Respiratory zone starts at respiratory bronchiole
which consists mainly millions of alveoli.
 Alveoli consist of
• Type I cells (squamous epithelium) and basal laminae scattered among
type I cells
• Type II cells (cuboidal epithelium)
» Secrete surfactant
• Macrophages that destroy foreign materials, such as bacteria
• Surfactant is a mixture of phospholipids(dipalmitoyl-phosphatidyl-
choline)
• It protects alveoli from collapse during expiration.
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40. Alveoli
 Features of alveoli
– Surrounded by elastic fibers.
– Interconnect by way of alveolar pores
– Internal surfaces
 A site for free movement of alveolar macrophages.
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41. ALVEOLAR CAPILLARY PLEXUS
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42. Pleura and Pleural Cavities
• The outer surface of each lung and the adjacent internal
thoracic wall are lined by a serous membrane called pleura.
• The outer surface of each lung is tightly covered by the
visceral pleura.
• while the internal thoracic walls, the lateral surfaces of the
mediastinum, and the superior surface of the diaphragm are
lined by the parietal pleura.
• The parietal and visceral pleural layers are continuous at the
hilus of each lung.
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43. Pleural Cavities
• The potential space between the serous membrane layers is a
pleural cavity.
• The pleural membranes produce a thin, serous pleural fluid
that circulates in the pleural cavity and acts as a lubricant,
ensuring minimal friction during breathing.
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44. Diagram of the Pleurae and Pleural
cavities
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45. Lungs
• A pair of respiratory organs situated in the thoracic cavity.
• Each is cone-shaped with anterior, lateral and posterior surfaces
contacting ribs
• Superior tip is apex, just deep to clavicle
• Concave inferior surface resting on diaphragm is the base.
• The lungs are heavier in the male than in the female, their
proportion to the body being, in the former, as 1:37, in the latter as
1:43.
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46. Gross Anatomy of the Lungs
 Major landmarks of the lungs
– Apex, base, hilum, and root
 Left lung
– Oblique fissure divides it to
• Superior and inferior lobes
 Right lung
– Oblque and horizontal fissure
divides it to
• Superior, middle, and inferior
lobes
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47. • Hilus or (hilum)
Indentation on mediastinal (medial) surface
Place where blood vessels, bronchi, lymph vessel, and nerves enter
and exit the lung.
• Root of the lung
Above structures forming a pedicle invested with the pleura
attaching lung to mediastinum.
Main ones: pulmonary artery and veins and main bronchus
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48. Bronchopulmonary Segments
• Each lobe is made up of Bronchopulmonary segments separated by
dense connective tissue
– These are well defined sectors of the lung
– These are independent respiratory units
– Limit spread of infection
• Each Bronchopulmonary segment is aerated by a tertiary or
segmental bronchus
• The branch of pulmonary artery accompany the bronchus and lies
dorsolateral to it. Thus each segment has its own separate artery
• Pulmonary veins run in the inter-segmental planes, serving adjacent
segments thus each segment has more than one vein and each vein
drains more than one segment
• Thus a bronchopulmonary segment is not a bronchovascular
segment as it does not have its own vein
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49. Bronchopulmonary Segments
The right lung is subdivided
into three lobes with ten
segments:
• right upper lobe
– apical
– posterior
– anterior
• right middle lobe
– lateral
– medial
• right lower lobe
– superior
– anterior basal
– medial basal
– lateral basal
– posterior basal
The left lung is subdivided into
two lobes and thereby, into eight
segments:
• left upper lobe
– apicoposterior
– anterior
– superior lingular
– inferior lingular
• left lower lobe
– superior
– anteromedial basal
– lateral basal
– posterior basal
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50. Bronchopulmonary Segments
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51. Blood Supply
• The lungs have two functionally distinct
circulatory pathways.
• These are the pulmonary vessels, which convey
deoxygenated blood to the alveolar walls and
drain oxygenated blood back to the left side of
the heart.
• The much smaller bronchial vessels, which are
derived from the systemic circulation and provide
oxygenated blood to lung tissues which do not
have close access to atmospheric oxygen.
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52. Innervation of the Lungs
• The lungs are innervated by parasympathetic (vagal) and
sympathetic fibres.
• The parasympathetic fibres are derived from vagus. They
supply the bronchial muscles and glands and are
bronchoconstrictor and secretomotor.
• The sympathetic fibres are derived from 2nd to 5th spinal
segments and are inhibitory to the bronchial muscles and
glands. They relax the bronchial smooth muscle and also
have vasoconstrictor effects.
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53. Lymphatic drainage of Lungs
Lymphatic vessels originate in the subpleural
(superficial) and deep lymphatic plexuses
• The subpleural lymphatic plexus is superficial, lying
deep to the visceral pleura, and drains lymph from the
surface of the lung to the bronchopulmonary (hilar)
nodes
• The deep lymphatic plexus is in the lung and follows
the bronchi and pulmonary vessels to the pulmonary
nodes and then bronchopulmonary nodes located at
the root of the lung
• Lymph from the parietal pleura drains into lymph
nodes of the thoracic wall
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54. Thank You!
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