The document summarizes key anatomical features of the trachea and bronchi. It begins by describing the trachea's length, width, cartilage rings, and relations to surrounding structures from the cricoid cartilage to the carina. It then discusses the carina and variations in tracheal shape. The document proceeds to detail branches of the bronchi, their histological changes as they branch, and features of terminal bronchioles including the transition to respiratory bronchioles lined by cuboidal epithelium.

1. TRACHEA
and BRONCHIOLE
Dr. Mohanad

2. 2
Trachea (windpipe): Landmarks
 Length: 9-15 cm long 15 – 20 incomplete C SHAPE
rings of cartilage/ Bridged post. by trachealis muscle
 1.5-2.5 cm wide
 Begins at lower border of Cricoid Cartilage / C6
 Extends to second rib anteriorly and T4-T5 posteriorly
(Carina)
 Lined by ciliated columnar epithelium

3. 3
Tracheobronchial Anatomy

4. 4
Cricoid
Cricoid Cartilage
Cricothyroid
membrane
Thyroid gland
Thyroid
cartilage
Cricoid cartilage

5. 5
Trachea
 Variable shape
 Usually round, oval, oval with flattened post.
border
 Square
 Inverted pear
 Horseshoe
 Very pliable in children
 May deviate to the right at almost 90° in normal
expiratory film.

6. 6
Trachea: Carina
 Ridge on internal aspect
of last tracheal cartilage
 Right of the midline
 Lies at T5 level: T4 on inspiration / T6 on
expiration
 Normal angle: 65°
 Angle increases by 10° - 15° in recumbency
(relaxing)
 Angle slightly larger + symmetrical in children

7. 7
Carina
 Mucosa highly sensitive
to irritants: Cough
reflex
*

8. 8
Main carina:
Concepts of anterior and posterior

9. Tracheal appearances
A
B
C
D
E
F
Saber sheath Dynamic collapse Crescent shape collapse
Normal shape expansion during inhalation circumferential collapse

10. 10
Relations: Cervical
 Anterior:
 Isthmus anterior to 2nd,
3rd, 4th rings
 Inferior thyroid veins
 Strap muscles:
Sternohyoid, Sternothyroid
 Posterior:
 Oesophagus, recurrent
laryngeal nerves
 Lateral:
 Lobes of thyroid
 Common carotid artery

11. 11
Relations: Thoracic
 Anterior:
 Brachiocephalic a.
 Left common carotid
a.
 Left brachiocephalic v.

12. 12
Relations: Thoracic
 Posterior:
 Oesophagus
 Left recurrent laryngeal
n.

13. 13
Blood supply
 Upper trachea
 Inferior thyroid artery
 Lower part
 Branches of the
bronchial artery
 Venous drainage
 Inferior thyroid
venous plexus

14. Histology of Trachea

15. Trachea
 Lined with respiratory
epithelium (ciliated pseudo-
stratified columnar
epithelium.)
 “C”-shaped pieces of
hyaline cartilage protecting
airway while allowing for
swallowing
 Trachealis muscle (smooth
muscle) runs across
posterior wall of trachea
connecting ends of tracheal
cartilage

16. Trachea
Low power
Medium power
High power

17. 17

18. Pseudostratified
Ciliated columnar
epithelium
Loose
connecti
ve tissue
Hyaline cartilage
Connective tissue
TRACHEA

19. Tracheal Lining

20. Trachea
Mucosa
 Epithelium
-Pseudo stratified ciliated
columnar/ Respiratory
epithelium
Cells-Ciliated columnar cells
- Goblet cells
-Brush cells
- Basal cells
-Granule (kulchitsky) cells
-Clara cells( bronchiolar
cells) surfactant secretion
 Lamina propria - Elastic
fibre, Lymphocyte, Mast cells,
Blood vessels

21. Mucous blanket
 Covers the epithelial
lining
 Composed of
 -95% water
 -glycoproteins
 Carbohydrate lipids
 DNA
 Cellular debris
Two distinct layers
 Sol layer
 Gel layer
Cilia move through sol layer
and strike gel layer
propelling it toward mouth
At a rate of 2 cm/minute

22. Mucous
 Mucus produced by
 Goblet cells
 Found through terminal bronchioles
Submucosal (bronchial) glands
extend into laminar propria
 Innervated by vagus nerve
(parasympathetic)
 Produce 100 ml of secretions/day
 Disappear at end of terminal
bronchioles

23. Trachea
 Sub mucosa-
 Loose connective tissue
 Tracheal glands-Mixed
(serous &mucus) glands
 Blood vessels and ducts
 Cartilage &smooth muscle
layer-
 ”C” Shaped hyaline cartilage
having perichondrium and
chondrocytes
 Ends of cartilage connected
by smooth muscles
 Adventitia-fibro elastic tissue

25. Bronchus
 Two principal bronchi begin at
bifurcation of trachea
 Each bronchi subdivides into
successive generations of smaller
bronchi and reach the lung
 Each bronchus consists of extra-
pulmonary and intra-pulmonary part

26. Right Bronchus
 It is wider ,shorter and more
vertical
 Wider because supplies more
voluminous air, vertical because
trachea bifurcation deviates more
to right side
 Foreign body in the trachea is
usually aspirated more to the right
side
 It enters the root of the right lung
and reaches the Hilum at the level
of 5th thoracic vertebrae

27. Left Bronchus
 Longer, narrower and more oblique than right bronchus
Extra-pulmonary part
 5 cm in length
 It enters the lung at the hilum at the level of 6th thoracic
vertebrae.
Intrapulmonary part
 The left principal bronchus divides into upper and lower
bronchi to supply the respective lobe of left lung.
 It divides into ascending and descending branches which
supply the bronchopulmonary segments.

28. Main Stem Bronchi
 Right bronchus
 Wider
 More vertical
 5 cm shorter
 Supported by C
shaped cartilages
 20-30 degree angle
 First generation
 Left bronchus
 Narrower
 More angular
 Longer
 Supported by C
shaped cartilages
 40-60 degree angle
 First generation

30. Pulmonary bronchi
 Within the lung, the principal bronchus divides into
Secondary or lobar bronchi
 Each secondary bronchus divides
Into Segmental or Tertiary Bronchi.
 The area of the lung aerated by a
tertiary bronchus is known as
Bronchopulmonary segment.

32. 32

33. Subsegmental Bronchi
 4th to 9th generations
 Progressively smaller airways
 1-4 mm diameter
 At 1 mm diameter connective tissue
sheath disappears

36. Bronchus Histology
 Principal bronchus
-Same as trachea
 Secondary /Lobar bronchus
-Irregular hyaline cartilage
-Pseudo stratified ciliated
columnar
 Tertiary /Segmental
bronchus
-Columnar epithelium
-Patches of cartilage

37. 37

38. Intrapulmonary bronchus

39. Changes as bronchi become smaller
 Cartilage-irregular and smaller. Absent in
bronchioles.
 Muscle- increases as bronchi becomes
smaller.(Spasm of these muscles bring difficulty
in breathing in allergic conditions)
 Subepithelial Lymphoid Tissue-increases with
decrease in the diameter of bronchi.
 Glands-few.Absent in the walls of capillaries.
 Epithelium- pseudostratified ciliated columnar
epithelium in principal bronchi later simple ciliated
columnar,non-ciliated columnar and later
cuboidal in respiratory bronchioles

42. Terminal Bronchioles
 16th to 19th generation
 Average diameter is 0.5 mm
 Cilia and mucous glands begin to disappear
totally
 End of the conducting airway
 Canals of Lambert-interconnect this
generation, provide collateral ventilation

43. Bronchiole
 Terminal bronchiole
-Columnar epithelium
-No cartilage
- Smooth muscle +
-Clara cells present
 Respiratory bronchiole
-Cuboidal epithelium
-No mucous gland

44. Bronchiole

45. Ciliated cells
Basal cells
 Goblet cells
Brush cells
Small granule cells
Clara cells
Cells types found in Luminal Epithelium of Bronchioles

46.  Goblet cells: numerous and secrete mucous.
Mucous traps the dust particles and is moved by
ciliary action towards pharynx.
 Non-ciliated serous cells: secretes watery fluid
that keeps the epithelium moist
 Cells of Clara: are non-ciliated cells
predominantly seen in terminal bronchioles.
Secrete a fluid that spreads over the alveolar
surface forming a film that reduces surface
tension. May function as stem cells

47.  Basal cells: Multiply and transform into other
cell types replace the lost cells.
 Argyrophil cells: cells similar to diffuse
endocrine cells of the gut containing granules,
secrete hormones and active peptides including
serotonin and bombesin.
 Lymphocytes and other leucoctes may be
present in the epithelium.

49. 49

50. Bronchus and Bronchiole

51. What are these tissues?
51

52. Differences between Bronchi and
Bronchioles
Bronchioles
 No glands
 No cartilage
 No goblet cells
 Thick smooth muscle layer
 Presence of Clara cells
 Many elastic fibres

53. b = respiratory bronchiole with alveolus (a) in its wall. Most of the wall of the bronchiole has a
definite line of dark along it, signifying a cuboidal epithelium d & c = alveolar duct. Its wall consists
almost entirely of alveoli, which have only a simple squamous lining, too flat to be visible here.
e = alveoli (the smallest respiratory units)
f = blood vessel (branch of pulmonary artery still)
Respiratory bronchioles, alveolar
ducts, and alveoli

54. 54

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