Lungs,Pleura & Tracheo-bronchial Tree

1. LUNGS,PLEURA & TRACHEO BRONCHIAL TREE
Dr. Prabhakar Yadav
Associate Professor
Department of Human Anatomy
B.P. Koirala Institute of Health Sciences

2. lungs or pulmones:
are paired organs of Respiration which lie
on either side of the mediastinum
surrounded by the right & left pleural cavities
Air enters and leaves the lungs via main
bronchi, which are branches of the trachea.
pulmonary arteries deliver deoxygenated
blood to the lungs from the right ventricle of
the heart.
Oxygenated blood returns to the left atrium
via the pulmonary veins.
Right lung is larger and heavier weighing-700
g and left lung 650 g.

3. The lungs are separated from each other by the mediastinum, to which they are attached by the
roots of the lungs.

4. EXTERNAL FEATURES
Each lung -conical/pyramidal shaped .
1. Apex.
2. Base
3. Three borders
(anterior, posterior, and inferior).
4. Two surfaces (costal and medial).
medial surface= vertebral + mediastinal part.
side determination:

5. Apex : blunt
extends into the root of the neck
• 3 cm superior to the anterior end of the 1st
rib
• 2.5 cm above the medial 1/3 of the clavicle
• covered by cervical pleura and suprapleural
membrane.
• Is grooved by the subclavian artery on the
medial side and in front.

7. Base :
• semilunar and concave.
• rests on diaphragm which separates
--right lung from the right lobe of the liver,
--left lung from the left lobe of liver, fundus of
stomach, and spleen

8. Anterior border : thin & shorter than the posterior border.
On right side -vertical
On left side- a wide cardiac notch below the level of the fourth costal cartilage.
The heart and pericardium are uncovered by the lung in the region of this notch.

9. Posterior border : thick and ill defined.
It corresponds to the medial margins of the heads of the ribs.
It extends from the level of the seventh cervical spine to the tenth thoracic spine.
Inferior border :separates the base from the costal and medial surfaces.

10. Costal surface: large and convex.
It is in contact with the costal pleura and the overlying thoracic wall.

11. Medial surface:
posterior or vertebral part : related to vertebral bodies ,intervertebral discs, posterior
intercostal vessel & splanchnic nerves
Anterior or Mediastinal part: related to cardiac impression, hilum and a number of
other impressions which differ on the two sides.

13. LOBES AND FISSURES
Right lung: 3 lobes (upper, middle and lower)
2 fissures(oblique and horizontal).
Left lung: 2 lobes
1 fissure (oblique)
oblique fissure:
cuts into the whole thickness of the lung,
except at the hilum.
It passes obliquely downwards and forwards,
crossing the posterior border about 6 cm
below the apex and the inferior border about
5 cm from the median plane.
Lower lobe is more posterior and the upper
and middle lobe more anterior.
It separates superior and middle lobes from
the inferior lobe
5cm
6cm

14. oblique fissure :
in left lung runs obliquely
downwards and forwards
crossing the posterior border
about 6 cm below the apex and
inferior border almost at its
apex.
• separates the superior lobe
from the inferior lobe.
6cm

15. In right lung:
horizontal fissure :
passes from the anterior border up to
the oblique fissure and separates a
wedge-shaped middle lobe from the
upper lobe.
Fissure runs horizontally at the level of
the fourth costal cartilage and meets the
oblique fissure in the midaxillary line.
The tongue-shaped projection of the left
lung below the cardiac notch is called
the lingula. It corresponds to the middle
lobe of the right lung.

16. Medial part of the superior lobe is
partially separated by a fissure which
contains the terminal part of the azygos
vein, enclosed in the free margin of a
mesentery derived from the mediastinal
pleura. This is termed azygos lobe .

17. ROOT OF THE LUNG:
is a short broad pedicle connecting the medial surface of the lung with the
mediastinum.
It consists of structures entering and leaving the lung at hilum.
roots of the lungs lie opposite the bodies of the fifth, sixth and seventh thoracic
vertebrae & is surrounded by a tubular sheath derived from the mediastinal pleura.
Hilum: is area on the mediastinal surface of the lung through which structures enter or
leave the lung.

18. Contents of root:
1.Principal bronchus on the left side, and epart-erial and hyparterial bronchi on right side.
2.One pulmonary artery.
3.Two pulmonary veins, superior and inferior.
4.Bronchial arteries, one on the right side and two on the left side.
5.Bronchial veins.
6.Anterior and posterior pulmonary plexuses of nerves.
7.Lymphatics of the lung.
8.Bronchopulmonary lymph nodes.
9.Areolar tissue

19. ARRANGEMENT OF STRUCTURES IN THE ROOT OF THE LUNG AT THE HILUM
From before backwards ( similar on the two sides)
(a) Superior Pulmonary vein
(b) Pulmonary artery
(c) Bronchus (left principal bronchus on the left side,
and eparterial, and hyparterial bronchus on the
right side).
Mnemonic: VAB

20. Right side Left side
Eparterial bronchus
Pulmonary artery Pulmonary artery
Hyparterial bronchus Left principal bronchus
Inferior pulmonary vein Inferior pulmonary vein
From above downwards (it differs on two sides):

21. RELATIONS OF THE ROOT OF THE LUNG
Anterior:
• Phrenic nerve.
• Anterior pulmonary plexus.
• Superior vena cava (on right side only).
Posterior:
• Vagus nerve.
• Posterior pulmonary plexus.
• Descending thoracic aorta (on left side only).
Superior:
• Arch of azygos vein (on right side only).
• Arch of aorta (on left side only).
Inferior:
• Pulmonary ligament.

22. Right lung Left lung
Size and shape Larger, shorter, and broader Smaller, longer, and narrower
Weight 700 g 650 g
Lobes Three (upper, middle, and
lower)
Two lobes (upper and lower)
Fissure Two (horizontal and oblique) One (oblique)
Anterior border Straight Not straight (presents a
cardiac notch)
Hilum Two bronchi (eparterial and
hyparterial)
One bronchus (left principal
bronchus)

23. ARTERIAL SUPPLY OF THE LUNGS
1. Bronchial arteries.
2. Pulmonary arteries.
BRONCHIAL ARTERIES
supply nutrition to the bronchial tree
and pulmonary tissue.
right lung is supplied by one bronchial
artery, which arises from the right
third posterior intercostal artery or
from upper left bronchial artery.
Left lung is supplied by two bronchial
arteries, which arise from descending
thoracic aorta,
Upper bronchial artery opposite fifth
thoracic vertebra and
lower bronchial artery just below the
left bronchus.

24. ARTERIAL SUPPLY OF THE LUNGS
Pulmonary arteries:
Deoxygenated blood is brought to the lungs
by the pulmonary arteries and oxygenated
blood is returned to the heart by
the pulmonary veins.
There are precapillary anastomoses
between bronchial and pulmonary arteries.
These connections enlarge when any one
of them is obstructed in disease.

25. VENOUS DRAINAGE:
The venous blood from the first one or
two divisions of the bronchi is carried by
bronchial veins.
Two bronchial veins on each side.
right bronchial veins drain into the azygos
vein.
left bronchial veins drain either into
• left superior intercostal vein or
• accessory hemiazygos vein.
greater part of the venous blood is
drained by the pulmonary veins two on
each side

26. Lymphatic Drainage:
two sets of lymph vessels :
1.Superficial vessels.
2. Deep vessels.
Superficial lymph vessels:
drain peripheral lung tissue lying beneath the visceral pleura forming superficial (subpleural)
plexus which drain into the bronchopulmonary (hilar) lymph nodes.

27. Lymphatic Drainage:
Deep lymph vessels:
drain the bronchial tree, pulmonary vessels
and connective tissue septa forming deep
plexus which run towards the hilum to drain
into the bronchopulmonary nodes.
superior and inferior tracheobronchial lymph
nodes,
pre- and paratracheal lymph nodes,
right lymphatic duct on the right side
thoracic duct and left sides .

28. Parasympathetic nerves are Sympathetic nerves are
Motor to the bronchial muscles,
and on stimulation cause bronchospasm
Inhibitory to the bronchial muscles,
and on stimulation cause bronchodilatation
secretomotor to the mucous glands of the
bronchial Tree
inhibitory to the mucous glands of the
bronchial tree
vasodilatation vasoconstriction
NERVE SUPPLY:
parasympathetic fibres derived from the vagus
sympathetic fibres derived from T2 to T5 spinal segments
Afferent impulse arising from the bronchial mucous membrane and stretch receptors in the
alveolar walls pass to the central nervous system through both sympathetic and
Parasympathetic fibres.

29. BRONCHIAL TREE:
trachea divides, at the level of the lower
border of T4 vertebra (Carina)
, into two primary (principal) bronchi—right
and left.
Right principal bronchus:
is shorter, wider, and more vertical.
is 1 inch (2.5 cm) long
Makes angle of 25° with tracheal bifurcation
Left principal bronchus :
is longer,narrower, and more horizontal .
is 2 inches (5 cm) long
Makes angle of 45° with tracheal bifurcation
principal bronchus- divides into secondary
(lobar) bronchi, one for each lobe.
Each lobar bronchus divides into tertiary or
segmental bronchi, one for each
bronchopulmonary segment
Clinical:
Postural drainage:

30. segmental bronchi divide repeatedly to
form terminal bronchioles which further
divides to form respiratory bronchioles
Respiratory bronchiole aerates a small
part of the lung known as a pulmonary
unit
Each pulmonary unit consists of
(a) alveolar ducts,
(b) atria,
(c) air saccules, and
(d) alveoli
Bronchoscopy

31. BRONCHOPULMONARY SEGMENTS
well-defined, wedge shaped, anatomic, functional & surgical sectors of the lung, which
are aerated by tertiary (segmental) bronchi.
Each segment has segmental bronchus, segmental artery, autonomic nerves & lymph
vessels
Segmental vein lies in connective tissue between adjacent bronchopulmonary
segment

35. Applied Anatomy:
Usually infection of a segment remains restricted to it, although tuberculosis, bronchogenic
carcinoma may spread from one segment to another.
Segmental resection:

36. THE PLEURA:
pleura is a serous membrane which is lined by mesothelium (flattened epithelum) -
secretes a watery lubricant—the serous fluid.
pleural sacs invaginated by lung
parietal pleura,
visceral or pulmonary
pleura
pleural cavity

37. two layers are continuous with each other around the hilum of the lung

38. Visceral Pleura (Pulmonary Pleura)
completely covers the surface of the lung
except at the hilum and along the
attachment of the pulmonary ligament
where it is continuous with parietal
pleura .
It extends into the depths of the fissures
of the lungs & is firmly adherent to the
lung surface and cannot be separated
from it.

39. Parietal Pleura
is thicker than the visceral pleura.
divided into:
1. Costal pleura. (dome of pleura or
pleural cupola).
2. Diaphragmatic pleura.
3. Mediastinal pleura.
4. Cervical pleura.
Costal pleura:
• lines the inner surface of the
thoracic wall to which it is loosely
attached by endothoracic fascia
Diaphragmatic pleura:
• covers the superior surface of the
diaphragm.
• is continuous with mediastinal
pleura medially and costal pleura
laterally.

40. Mediastinal pleura:
• lines the mediastinum surface.
• It is reflected over the root of the
lung and becomes continuous with
the visceral pleura.
Cervical pleura:
• extends into the root of the neck
-1 inch (2.5 cm) above the medial 1/3
of clavicle
- 2 inches (5 cm) above the 1st costal
cartilage,
• covers the apex of lungs.
• it is covered by suprapleural
membrane

41. Relation of cervical pleura:
anteriorly :
subclavian artery and scalenus anterior
posteriorly :neck of the first rib and structures
lying over it
laterally : scalenus medius
medially: large vessels of the neck

42. Pulmonary Ligament:
parietal pleura surrounding
the root of the lung extends
downwards beyond the root
as a fold called the pulmonary
ligament.
contains :
• loose areolar tissue
• few lymphatics.
Function:
• provides a dead space into
which the pulmonary veins
can expand during increased
venous return as in exercise
• lung roots can also
descend into it with the
descent of the diaphragm

43. RECESSES OF THE PLEURA
in areas of pleural reflection on to the
diaphragm and mediastinum, the space
between the parietal and visceral pleura is
greatly expanded which are are called
pleural recesses- serve as reserve spaces of
pleural cavity for the lungs to expand during
deep inspiration.
1. Costodiaphragmatic recesses (right and
left).
2. Costomediastinal recesses (right and
left).
3 more small recesses
• Right and left retroesophageal recesses
• Infracardiac recess

44. Costodiaphragmatic recess :
• between the costal and diaphragmatic
pleurae.
• Vertically it measures about 5 cm
• lies opposite 8th–10th ribs along the
midaxillary line.
• are the most dependent parts of the
pleural cavities
Applied:
Pleurisy: inflammation of pleura- collection
of fluid – pleural effusion
Pleural effusion : obliterates
costodiaphragmatic recess

45. Costomediastinal recess :
• located anteriorly between the costal
and mediastinal pleurae.
lies between sternum and costal cartilages.
• Right costomediastinal recess is occupied
by the anterior margin of the right lung
even during quiet breathing.
• left costomediastinal recess is large due
to the presence of cardia cnotch

47. Applied Anatomy:
Hemothorax:
Hydrothorax:
Empyma:
Pneumothorax:
hydropneumothorax:
Paracentesis Thoracis:

48. NERVE SUPPLY OF THE PLEURA
visceral pleura :
• develops from splanchnopleuric layer
• supplied by the autonomic nerves.
 sympathetic nerves are derived from T2-T5
 parasympathetic nerves from vagus nerve
• is insensitive to pain.
parietal pleura
• develops from somatopleuric layer
• supplied by the somatic Nerve
 Costal and peripheral part of the diaphragmatic pleura - intercostal nerves.
(Applied: irritation causes referred pain along intercostal nerve to thoracic or
abdominal wall)
 Mediastinal and central part of the diaphragmatic pleura- phrenic nerve.
(Applied: irritation causes referred pain on tip of shoulder)
• is sensitive to pain

49. BLOOD SUPPLY AND LYMPHATIC DRAINAGE OF THE PLEURA
Blood supply of parietal pleura is same as that of the thoracic wall – intercostal,
internal thoracic and musculophrenic arteries
veins drain mostly into the azygos and internal thoracic veins
lymphatics drain into the intercostal, internal mammary, posterior mediastinal and
diaphragmatic nodes.
blood supply of the visceral pleura is same as that of the lung.- bronchial arteries
while the veins drain into bronchial veins
Lymphatics is drained by bronchopulmonary lymphnodes.

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