anatomy of tracheobroncial tree

ANATOMY OF TRACHEOBRONCIAL TREE

By,Dr. Arun Kumar Dept of AnesthesiologyYMC.

Moderator: Dr. Harish Hegde.

TRACHEA

TRACHEA

•Extends from lower border of cricoid cartilage.

•At the level of C6 vertebra.•Length of about 15-20 cm.•Intermittently strengthened by cart. Rings.•At 6TH tracheal ring it goes intrathoracic. •At the level of T5( angle of louis, 2nd

intercostal space), bifurcation occurs.•Right and left bronchus.

THE BRONCHUS

•Left and right bronchus.•Adults right is shorter and in a more acute

angle. (hence ETT, suctioning, foreign body enters easily).

• Its still out of lung parenchyma, right 2.5cm, left 5cm.

•Right divides into 3 branches and left 2.•Futher division to medium, small

bronchi(0.8-4mm), and bronchioles(0.8mm)

THE BRONCHIOLES

•Branches from bronchus with diameters <0.8mm.

•Do not have cartilages.•Classified into 2 types: terminal and

respiratory.•Terminal: each of these leads to 3 resp.

bronchioles -> 4 generations of alveolar ducts.

ALVOELI

•Site of gas exchange.•Formed of single layer of cells.•Pneumocytes I, II.•Other cells pulm macrophages, mast cells,

lymphocytes.•Bound by tight gap junctions.•Supported by elastic connective tissue.•Avg diameter 0.05- 0.33mm.•Sorrounded by pulm vessels.

CARTILAGES

•The cartilages in the trachea is of hyaline,•Its semicircular, deficient posteriorly,•Ends connected by a fibroelastic band.•Primary function: to prevent collapse of the

trachea.•Splits at the carina to cover the bronchus.•As bronchi becomes intrapulmonary, it

changes discretely into cartilage plates.•Dissappears in airway of diameter

<0.6mm.

MUSCLE• 2types inner circular, outer longitudinal(predominant in

children).

• Distributed in a geodesic network like pattern.

• Striated. Autonomic innervation (bronchodialator symp)

• Primary function: change size of tube during stages of respiration.

• It becomes thinner with division but relative thickness increases.

• Highest in terminal bronchioles: prolonged spasm. Autonomic innervation.

Epithelium and defence mech.

•Lined by columnar pseudostratified epithelium.

•Namely goblet, serous, ciliated cells mainly produce mucus.

•No mucus glands in bronchioles.•Ciliated epithelium brushes mucus out of

the airway.•?K-cells, clara cells- supportive.•Lymphocytes, “globule” lymphocyes:

defence.

Blood supply•Mainly by the bronchial arteries. 1 to left

side, 2 to right.•Left arises from ant. Aspect of descending

aorta.•Right has variable origins: 1/3 intercostal,

rt.subclavian, internal thoracic arteries.•Has good anastomoses in the adventitia of

the bronchus.•Venous plexuses drain airway to bronchial->

azygous -> hemiazygous-> intercostal veins.

BRONCHO PULMN. SEGMENTS

•It is a unit of lung parenchyma, distinct with its own segmental bronchus and a pulmonary artery, which is separated from the other by septa.

•Totally 20 present.

•Divided by the brochus which enters the lung.

Right side

•3 segmental bronchi: •UPPER: 1. Apical, 2. posterior, 3. anterior.

•MIDDLE: 1. lateral, 2. medial.

•LOWER: 1. apical, 2.medial basal(cardiac), 3.ant.basal, 4. post. Basal, 5. lat. Basal.

Left side

•UPPER: 1. apical, 2. posterior 3. Anterior.

•LINGULAR: 1. superior, 2. Inferior.

•LOWER: 1. apical, 2. ant.basal, 3. post.basal, 4. lat.basal.

Brocho pulmn segments contd.

•This anatomical division has made lung resection surgeries easier.

•Lung radiodiagnosis.•postural drainage.•Visualising the interiors of the bronchi.•Infections of the segments remains

restricted to it.

•Benumoff textbook of airway management.

•Miller textbook of anesthesia 7th edition.

•Morgan, clinical anesthesiology 4th edition.

•Ellis, Feldman, Griffith:Anatomy for anesthesiologists.

•BD Chaurasia, human anatomy 4th edition.

•World wide web.