the one who is always traveler

1. The Lungs
&
Pleurae
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2. The Pleurae
• Double layered serous
membrane lined with
mesothelium (simple squamous
epithelium)
1. parietal pleura (outer) –
adherent to body wall
2. visceral pleura (inner) -
attached with lung and its
fissures
 The two layers are continuous
around hilum
 A potential space between the
two layers is called pleural
cavity
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3. The parietal pleura
• lines the pulmonary cavities,
thereby adhering to the thoracic
wall, mediastinum, and
diaphragm.
• It is thicker than the visceral
pleura
• Parts of the parietal pleura
 Diaphragmatic
 Mediastinal
 Costal
 Cervical (copula
• It also encloses the great
vessels running to the lung root
• Projects into the root of the neck
as the copula
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4. Con’t…
Costovertebral or costal pleura
– covers the internal surfaces of the thoracic wall.
– It is separated from the internal surface of the thoracic wall
(sternum, ribs and costal cartilages, intercostal muscles and
membranes, and sides of thoracic vertebrae) by endothoracic
fascia.
Mediastinal pleura
– covers the lateral aspects of the mediastinum,
– It continues superiorly into the root of the neck as cervical
pleura.
– It is continuous with costal pleura anteriorly and posteriorly and
with the diaphragmatic pleura inferiorly.
Diaphragmatic pleura
– covers the superior (thoracic) surface of the diaphragm on each
side of the mediastinum,
– except along its costal attachments (origins) and where the
diaphragm is fused to the pericardium
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5. Con’t…
Cervical pleura
– covers the apex of the lung (the part of the lung
extending superiorly through the superior thoracic
aperture into the root of the neck
– It is a superior continuation of the costal and
mediastinal parts of the parietal pleura.
– The cervical pleura forms a cup-like dome (pleural
cupula) over the apex
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7. The visceral pleura
• Covers surfaces and fissures
of lungs
• Firmly adherent to lung
• Insensitive to pain
• Provides a moistened and
lubricated surface for lung
movement
• Adhesions with the parietal
pleura may result from
infections, inflammatory
reactions and lung immobility
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8. Pleurae ….
• Visceral and parietal pleurae are continuous at the
root of the lungs, where pulmonary artery and vein,
and bronchus penetrate the lung
• The continuity b/n parietal and visceral pleurae
surrounding the root of the lung extends
downwards as a fold called pulmonary ligament
– It provides a space into which pulmonary veins
can expand
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10. The Pleural cavity
• A slit like potential space b/n the parietal and visceral pleurae
• Represents a closed sac with no communication between right and
left parts
• Filled with a thin layer of pleural fluid secreted by the pleurae, this
lubricating fluid allows the lungs to glide without friction over the
thoracic wall during breathing movements
• The fluid also holds the parietal and visceral pleurae together
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11. Pleural recesses
• Cavity not occupied by the
lung
• Reserve spaces for lung to
expand
Costodiaphragmatic
recesses
 inferiorly between
costal and
diaphragmatic pleura
 5cm vertically, extends
from 6-10 ribs
 first part of pleural
cavity to be filled with
effusion
Costomediastinal recesses
 anteriorly between
costal and mediastinal
pleura
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12. Innervation and blood supply of the pleura
• Parietal pleura
 Cervical, costal and peripheral diaphragmatic portion -
intercostal nerves and vessels
 Central portion of diaphragmatic and mediastinal – phrenic
nerve and internal thoracic & musculophrenic vessels
 Sensitive to pain
 Venous drainage - intercostal veins, internal thoracic and
azygos
 Lymphatics – intercostal, internal mammary, diaphragmatic
& posterior mediastinal lymph nodes
• Visceral pleura
 Sympathetic nerves derived from T4 & T5
 insensitive to pain
 vasculature and lymphatics are similar to lungs
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13. Clinical correlates
• Pneumothorax – presence of air in the pleural cavity
• Haemothorax - when blood accumulates
• Hydrothorax - when fluid accumulates
• Pleurisy – inflammation of the pleura  rough surface 
rubbing  sound
• Regions of the pleura not protected by ribs – cupula, right
infrasternal, right and left costovertebral angles
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14. Pleuricentesis(pleural tab)
• Aspiration of fluid from the
pleural cavity
• Mostly done in the 9th
intercostal space at mid axillary
line
• the needle should be inserted
through middle part of intercostal
space to avoid injury to
neurovascular bundle
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15. The Lung
• The lungs occupy all of the thoracic cavity except the
mediastinum
• Each cone shaped lung is suspended in its own pleural
cavity and connected to the mediastinum
External anatomy
 Spongy in texture and pink in colour in young but
mottled black by carbon particles in adults
 Has
 An apex
 A base
 Three borders:
– Anterior
– Posterior
– Inferior
 Three surfaces (costal, mediastinal, and
diaphragmatic)
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17. Lungs: anterior view
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18. Lungs: posterior view
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19. Lungs : Apex
• Blunt, lie above anterior end of
first rib
• Projects into the root of neck
through the thoracic inlet
extending 1 inch above the
medial 1/3 of clavicle
• Anteriorly grooved with
subclavian artery
• Covered by cervical pleura and
suprapleural membrane
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20. The base (diaphragmatic surface)
 Semilunar and concave
 Rests on diaphragm which separates the right lung from right
lobe of liver and left lung from fundus of stomach
 It is found at the level of
• the 6th costal cartilage in the mid-clavicular line
• the 8th costal cartilage in the mid-axillary line
• rib 10 dorsally
 Due to the position of the liver, the base of the right lung is
broader than that of the left lung
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21. Borders
Inferior
• Separates the base from costal and
medial surfaces
Anterior
• Thin and short
• Right vertical
• Left shows wide cardiac notch
• where costal and mediastinal meet
anteriorly
Posterior
• Thick and ill defined
• Correspond to medial margins of
head of ribs
• Extends from 7 cervical spine to 10
thoracic spine
• where costal and mediastinal meet
posteriorly
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22. Surfaces
• The costal surface
– large, smooth, and
convex
– related to the costal
pleura
– Its posterior part is
termed as vertebral part
of the costal surface
• Mediastinal surface
– Related medially to the
mediastinum and
posteriorly to sides of
the vertebrae
– Includes the hilum of
the lung
• Diaphragmatic surface
– Rests on the convex
dome of the diaphragm
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23. The root of the lung
• Short broad pedicle which
connects medial surface of
lung with mediastinum
• Formed by structures
which leave or enter the
lung at hilum
• Lie at level of T5-T7
Contents
A. Bronchus – posterior
 Left – divide after
entering, only one
 Right - divide before
entering: eparterial &
hyparterial
B. Pulmonary artery
 On the left – more
anterior and higher
 On the right – b/n
eparterial and 23
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24. C. Pulmonary veins – two in each,
superior and inferior
A. Superior – anterior and
inferior to pulmonary artery
and bronchus
B. Inferior – the most inferior
D. Bronchopulmonary lymph
nodes
E. Bronchial vessels
A. Bronchial artery - left two
(braches of descending
aorta) & right one (upper left
bronchial artery/3rd posterior
intercostal)
B. Bronchial veins - right to
azygos and left to accessory
azygos and hemiazygos
F. Pulmonary plexus –
parasympathetic + sympathetic
G. Lymphatics of lung
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25. The right lung
 The right lung has 3 lobes and 2 fissures
Horizontal fissure
 From anterior border of right lung at 4th costal cartilage to meet the
oblique fissure at mid axillary line
 divide the superior from the middle lobe
Oblique fissure
 b/n middle and inferior lobes
 from posterior border 6 cm below the apex (at T3) to the inferior border
5cm from median plane
 Examination of the superior lobe is done on the anterior chest wall,
whereas examination of the inferior lobe is done posteriorly below the
scapula
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26. Mediastinal relation of right lung
• Pericardial impression –
anterior to the hilum by
right atrium
• IVC impression –
posterior to pericardial
mark
• SVC
• Esophageal - large
vertical groove behind the
hilum and impression of
trachea
• Trachea – behind SVC
• Azygos groove – behind
esophageal
• Ascending aorta and
thymus – anterior to hilum
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27. The left lung
 Has a superior and
inferior lobe divided by an
oblique fissure
 Large cardiac notch found
on the mediastinal
surface
 The lingula - an anterior
projection of the superior
lobe below cardiac notch
overlies the anterior
aspect of the heart
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28. Mediastinal impression of left lung
A. Cardiac impression –
left ventricle
B. Arch of aorta – above
the root
C. Thymus – above the
root anterior to the
groove for arch of
aorta
D. Descending aorta –
posterior to the hilum
E. Esophageal – posterior
to subclavian superior
to the arch of aorta
F. Left subclavian artery
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29. Right lung Left lung
Size Larger and heavier
(700gm)
Small and lighter
(600gm)
Length and width Shorter & broader Longer and narrower
Anterior border Straight Cardiac notch &
lingula
Lobes and fissures Three lobes & two
fissures
Two lobes & one
fissure
Arterial supply One bronchial
artery
Two bronchial
arteries
Arrangement in
the hilum
Differences between right and left lung
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30. Structural features as we gradually transit from one
type of airway to the next
1. Epithelium
– Tall, pseudostratified columnar ciliated epithelium in larynx
and trachea
– Simple cuboidal non-ciliated in small airways
– Goblet cells (mucus secreting) gradually disappear
2. Smooth muscle
– Lies deep to mucosa (except in trachea)
– Becomes increasingly important as airway diameter
decreases
– Absent in respiratory bronchioles
– Regulates calibre of airway and hence resistance to air
flow
• Sympathetic - muscle relaxation
• Parasympathetic - constriction
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31. 3. Serous and mucous glands
– Progressively less numerous in narrower airways
4. Cartilage
– Supporting skeleton for larynx, trachea and bronchi
– Maintains patency during respiration
– cartilage rings are gradually replaced with isolated plates
of hyaline cartilage
– Gradually diminishes; absent beyond tertiary bronchi
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32. The Conducting Zone of the Bronchial tree
The primary bronchus
• The right and left primary
bronchi are formed by the
division of the trachea at the
level of T4 in the mediastinum
• The right is shorter, wider and
more vertical than left
 Inhaled particles tend to pass
more frequently to the right
lung (the posterior basal
segment is most likely)
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33. Con’t…
The mucosa Layer
• the larger bronchi is structurally similar to the tracheal mucosa
except for the organization of cartilage and smooth muscle.
• In the primary bronchi most cartilage rings completely encircle
the lumen, but as the bronchial diameter decreases, cartilage
rings are gradually replaced with isolated plates of hyaline
cartilage.
Lamina propria
• is a layer of crisscrossing bundles of spirally arranged
smooth muscle, which become more prominent in the smaller
bronchial branches
• contains elastic fibers and abundant mucous and serous
glands ___ ducts open into the bronchial lumen.
• Numerous lymphocytes are found both within the lamina
propria and among the epithelial cells
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35. The lobar bronchi
• Each primary bronchus
enters the hilus of the
lung and divides into
secondary or lobar
bronchi
• Right – 3; upper,
middle & lower
• Left - 2; upper & lower
• divide into the tertiary
or segmental bronchi
which supply
bronchopulmonary
segments of the lung
• The tertiary bronchus
is joined by a tertiary
division of the
pulmonary artery
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36. Tertiary (segmental)
bronchi
• Right (10) and Left (9)
• Right superior lobar
bronchi - apical, posterior
and anterior tertiary
bronchi
• Left superior lobar-
apicoposterior, anterior,
superior lingular and
inferior lingular segmental
bronchi
• Right middle lobar -
medial and lateral tertiary
bronchi
• Right and left inferior
lobar- superior, medial
basal, lateral basal,
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37. Bronchopulmonary segments
• The smallest, functionally independent region of a lung that
can be isolated and removed without affecting adjacent
regions
• Pyramidal-shaped segments of the lung, with their apices
facing the lung root and their bases at the pleural surface.
• Separated from adjacent segments by connective tissue
septa.
• Supplied independently by a segmental bronchus and a
tertiary branch of the pulmonary artery.
• Named according to the segmental bronchi supplying them.
• Drained by intersegmental parts of the pulmonary veins that lie
in the connective tissue between and drain adjacent
segments.
• The right lung has 10 bronchopulmonary segments and the left
lung has 9.
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38. Bronchopulmonary segments
Right lung
I. Upper
I. Apical
II. Anterior
III. Posterior
II. Middle
I. Medial
II. Lateral
III. Lower
I. Apical
II. Anterior basal
III. Posterior basal
IV. Medial basal
V. Lateral basal
Left lung
I. Upper
I. Apicoposterior
II. Anterior
III. Superior lingular
IV. Inferior lingular
II. Lower
I. Apical
II. Anterior basal
III. Posterior basal
IV. Medial basal
V. Lateral basal
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39. Bronchopulmonary segments - right lung
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40. Clinical significances of bronchop… s
• Limit the spread of some diseases within the lung,
because infections do not easily cross the connective
tissue partitions between them
• Because only small veins span these partitions, surgeons
can neatly remove segments without cutting any major
blood vessel
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41. Bronchioles
• 1mm diameter or less
• terminal branches of tertiary bronchi
Mucosal layer
• have neither cartilage nor glands in their mucosa
• epithelium is a respiratory epithelium changing to ciliated
simple columnar or cuboidal
• Goblet cells gradually decreases with the decreasing
tubular size.
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42. Con’t…
lamina propria
• is composed largely of smooth muscle and elastic fibers
• The musculature of both the bronchi and the bronchioles is
under the control of the vagus nerve and the sympathetic
nervous system,
• Stimulation of the vagus nerve decreases the diameter of
these structures
• Sympathetic stimulation produces the opposite effect
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44. Terminal bronchioles
• the distal part of the
conducting portion
• lined by simple
cuboidal epithelium
containing clara
cells, no goblet
cells
• Clara cells - ciliated
cells, secrete
surfactant and
metabolize air bone
toxins
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45. The Respiratory Zone
• Consists of respiratory bronchioles, alveolar duct &
alveolar sacs
• Respiratory bronchioles
– Transitional zone between the conducting and
respiratory part
– Contain dispersed alveoli
– Lined by ciliated cuboidal epithelium that becomes
continuous with squamous alveolar lining cells
– Each give 2-11 alveolar ducts
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47. Alveolar ducts
• The ducts lead into
terminal clusters of alveoli
called alveolar sacs
• Each alveolar duct gives 5-
6 alveolar sacs which give
rise to alveoli
• Wall: smooth muscle cells
+ collagen and elastic
fibers
• Lined by squamous
alveolar cells
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48. Alveolus
• Saclike evagination
• Lined by flattened epithelial cells
• Fibers around openings merge to form a supporting
framework for lung parenchyma
• Alveolar wall
– Consists of 3 components: epithelium, supporting
tissue and blood vessels
• Cells of the alveoli
– Pneumocyte type I cells - form the alveoli walls
– Pneumocyte type II cells - secrete a phospholipid called
surfactant that coats the alveolar surfaces which
prevents collapse of alveoli walls
– Alveolar macrophages – phagocytic cells, trap dust
particles, carry to bronchioles for ciliary action
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49. Con’t…
• Lung alveoli have three other features
– Surrounded by fine elastic fibers
– pores connect adjacent alveoli
• Allow for pressure equalization
• Alternative air routes for blocked bronchi
– The external surfaces of the alveoli are densely
covered with a web of pulmonary capillaries
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50. Inner wall of alveolus
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51. Outer wall of alveolus
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52. The Respiratory Membrane
• 0.5 um thick
• Gaseous diffusion barrier between blood and alveolar
air
• Capillaries form plexus around alveoli
• Basement membrane of capillaries fuses with that of
epithelium which provide interface of minimal thickness
• Gas exchange occurs by simple diffusion across the
respiratory membrane
• Respiratory epithelium at thinnest site consists of
– basement membrane of type I cells
– capillary basement membrane
– Capillary endothelium
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54. Alveolar walls and alveolar cells. Stain: hematoxylin and eosin. High
magnification
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55. Bronchial tree:
Trachea
Primary bronchi
Secondary bronchi
Tertiary bronchi
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
alveolar sacs
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56. Blood supply of the Lungs Pulmonary arteries
• Two in number; one for each
lung
• Derived from the bifurcated
pulmonary trunk
• Carry poorly oxygenated
blood to lungs for
oxygenation
• Give off branch to superior
lobe before entering hilum
• The right pulmonary artery is
crossed over by the azygos
vein whereas the left
pulmonary artery is crossed
over by the arch of the aorta
at T5
• Within the lung, divide into
lobar branches and then
segmental branches which
have a close relationship with
the tertiary bronchi in the
bronchopulmonary segments
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57. Bronchial arteries
• Supply blood to root of lungs,
supporting tissue and visceral
pleura
• Origin
 Right – one
• arise directly from the aorta.
• Most commonly it arises
indirectly
• the right 3rd posterior
intercostal artery),
• or from a common trunk
with the left superior
bronchial artery
 Left – two; thoracic aorta
• The small bronchial arteries
• Supply posterior to bronchi
• Give branch to esophagus
• Supply bronchial tree to respiratory
bronchioles
• Distal branches anastomose with
branches of pulmonary arteries
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58. Bronchial veins
• Drain only part of the
blood supplied to the
lungs by the bronchial
arteries
• distributed to or near the
more proximal part of the
roots of the lungs
• The rest is drained by
pulmonary veins
– visceral pleura,
– the more peripheral
regions of the lung
– the distal components of
the root of the lung
• Termination
 Right – azygos
 Left – accessory
hemiazygos/ left
superior intercostal
vein
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59. Pulmonary veins
• Four in number; two for each lung
• Carry well-oxygenated blood
• Begin from pulmonary capillaries veins join into larger
veins and drain into intrasegmental veins which drain into
intersegmental veins in the septa which join to form
pulmonary veins
• 2 lower veins - from the inferior lobe of each lung
• Upper right vein - from the superior and middle lobe of
the right lung
• Upper left vein - from the superior lobe of the left lung
• The pulmonary veins also drain oxygenated blood
supplied to the lungs by the bronchial arteries
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60. Lymphatic drainage of the Lungs
• Bronchopulmonary lymph
nodes - two sets of
lymphatics drain into
bronchopulmonary lymph
nodes at the hilum
– Superficial: from the
superficial part of the lung
– Deep: drain bronchial
tree, vessels and lung
tissue
• Tracheo-bronchial lymph
nodes – two groups; superior
and inferior located at the
bifurcation of trachea
• both nodes drains into
broncho-mediastinal
lymphatic duct
– Right – right lymphatic
duct
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61. Nerves of the Lungs
• The broncho-pulmonary plexus
supplies both parasympathetic &
sympathetic nerves to the bronchial
and vascular trees
• Parasympathetic fibers are
preganglionic vagal
– Secretomotor to glands in the
bronchial mucosa
– Motor to bronchial smooth
muscles – spasm
– Sensory
– Vasodilator to bronchial and
pulmonary vessels
• Sympathetic fibers are
postganglionic fibers from T2-T5
– vasomotor to arterial system
(vasoconstriction)
– Bronchodilator
– Inhibitory to bronchial glands
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