1. ANATOMY OF TRACHEOBRONCHIAL TREE
PRESENTED BY- Dr. CHITRA
MODERATOR-Dr.AJAY SOOD

2. Respiratory System

3. TRACHEA
It is a cartilaginous and membranous tube
EXTENT - from 6th cervical vertebra till the body of 5th thoracic vertebra
During expiration the bifurcation rises by one vertebral level and during inspiration may be lowered as far as 6th thoracic vertebra
LENGTH - 11cm
DIAMETER - 2 to 2.5cm
CHILDREN - smaller, deeper, more moveable

4. STRUCTURE
CARTILAGES-16to20 in no.,each forms an incomplete ring,which occupies anterior two third of circumference of trachea
Are placed horizontally above each other,separated by narrow intervals
4mm deep and 1mm thick
Outer surface is flattened in vertical direction and convex from inner side
Highly elastic,but may calcify in later stages
FIRST TRACHEAL CARTILAGE-broader,divided connected to lower end of cricoid by cricotracheal ligament
LAST TRACHEAL CARTILAGE-thick and broad in midlle, lower border is prolonged to a triangular hook shaped process which curves downward and backward between two bronchi

6. FIBROUS MEMBRANE-cartilages are enclosed in an elastic fibrous membrane which consists of two layers,one passes over the outer surface the other one over the inner surface
At upper and lower margins they blend together to form a single membrane
MUSCULAR TISSUES-two layers of non –striated muscles longitudinal and transeverse
Longitudinal fibres are external,consist of few scattered bundles only
Transeverse fibers(trachealis muscle) are internal,extends between the end of cartilages

7. MUCUS MEMBRANE-continous above with larynx and below with bronchus
Consist of areolar and lymphoid tissue,basement membrane,supporting stratified epithelium ,surface layer of which is columnar and ciliated
Beneath basement membrane there is a layer of longitudinal elastic fibre
Submucus layer,composed of loose meshwork of connective tissue
VESSELS AND NERVES-
ARTERIAL SUPPLY-Inferior thyroid arteries
NERVE SUPPLY-vagus nerve,recurrent nerve,sympathetic nerves

9. RIGHT BRONCHUS 2.5cm long Wider,shorter,more vertical
Divides into EPARTERIAL and HYPARTERIAL BRONCHUS based on right pulmonary artery

10. RIGHT UPPER LOBE BRONCHUS
It divides into three segmental bronchi which supply apical,anterior and posterior segments of upper lobe
APICAL SEGMENTAL BRONCHUS-divides into apical and anterior subsegmental branches
POSTERIOR SEGMENTAL BRONCHUS-divides into lateral and anterior subsegmental branches. It serves the posteroinferior part of superior lobe of lung
ANTERIOR SEGMENTAL BRONCHUS-runs anteroinferiorly to supply rest of the part of upper bronchus. Divides into lateral and anterior subsegmental branches

11. RIGHT MIDDLE LOBE BRONCHUS RIGHT LOWER LOBE BRONCHUS
Divides into lateral and medial subsegments
RIGHT LOWER LOBE BRONCHUS
Continuation of principal stem beyond the origin of middle lobe bronchus
Supplies 5 segments of the lung
Apical segmental bronchus
Medial basal segmental bronchus
Anterior basal segmental bronchus
Lateral and posterior basal segmental bronchus

13. LEFT BRONCHUS 5cm in length Smaller in caliber
Enters the lung opposite 6th thoracic vertebra
RELATIONS-passes beneath the aortic arch,crosses in front of oesophagus,thoracic duct,descending aorta,has left pulmonary artery at first above and then in front

14. LEFT UPPER LOBE BRONCHUS
Cranially it divides into anterior ,apical and posterior segmental branches
Caudally into superior and inferior lingual branches
LEFT LOWER LOBE BRONCHUS
Divides into apical segmental bronchus,medial basal,anterior basal,lateral and posterior basal branches

16. BRONCHI Right bronchus Left bronchus Wider More vertical shorter-
Right bronchus
Wider
More vertical
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

17. CLINICAL SIGNIFICANCE
Right main bronchus is more in line with trachea
Inhaled foreign bodies and gastric contents enter right bronchial tree
If patient is lying on his side,lateral subsegments of anterior and posterior segments are more likely to get such material
If patient is supine,then apical segmental bronchus which arise from right or left lower lobe bronchus is the most common part of lung for the aspirated material to collect

19. BRONCHOPULMONARY SEGMENTS
Anatomic,functional and surgical units of lung
23 divisons or generations are involved in dichotomous division,starting from trachea till alveolar sacs
Each lobar bronchus(secondary bronchus) gives off branches called segmental bronchus(tertiary bronchus)

20. As bronchi become smaller, cartilages also become smaller and fewer in no
Bronchioles are formed which are less then 1mm in dia,no cartilages and lined by ciliated columnar epithelium
Divide to form terminal bronchioles,which show delicate outpouchings from their wall
These are respiratory bronchioles,dia is 0.5mm,they end by branching into alveolar ducts

21. Each alveolar sac consist of around 17 alveoli
Each alveolus surrounded by rich network of blood capillaries
Gas exchange primarily occurs on thin side of alveolocapillary membrane,thick side provides structural support

22. ALVEOLI
Type I pneumocytes- large flattened cells, present a very thin diffusion barrier for gases
Type II pneumocytes- secretes surfactant,which decreases the surface tension between thin alveolar walls
macrophages

24. Subdivision of lung lobe
Pyramid shaped,apex towards lung root
Surrounded by connective tissue
Segmental bronchus,segmental artery,lymph vessels and autonomic nerves
Segmental vein lies between adjacent segments

26. BLOOD SUPPLY OF LUNGS
By bronchial arteries which are branches of descending aorta
NERVE SUPPLY OF LUNGS
Pulmonary plexus-efferent and afferent autonomic nerve fibres
Sympathetic efferent fibres produce bronchodilation and vasoconstriction
Parasympathetic efferent produces bronchoconstriction,vasodilation,increase glandular secretions