TRACHEA, BRONCHI, BRONCHIOLES - ANATOMY2021 - EASYMEDNOTES

TRACHEA, BRONCHI AND BRONCHIOLES

TRACHEA

The trachea is also know as windpipe.

It is a cartilaginous tube which connects the larynx to bronchi.

ANATOMICAL POSITION

  • It starts at the lower border of the cricoid cartilage in the neck.
  • It travels inferiorly into the superior mediastinum.
  • Bifurcation start at the level of sternal angle , It bifurcates into right and left bronchus
  • As it descends down, trachea will be anterior to the esophagus and it slightly inclines to the right side

STRUCTURE

  • The structure of the trachea is long tube like and c shaped rings are present and these c shaped are supported by trachialis muscle in the neck.
  • Trachea and bronchi are lined by ciliated pseudostratified columnar epithelium and goblet cells are scattered. which helps in producing mucus.
  • The combined movement of cilia and mucus forms the functional mucociliary escalator.
  • This will trap inhaled particles and pathogens which moves them out of the airways.

At the bifurcation of the primary bronchi and there will be a ridge of cartilage which is known as carina, it runs anteroposteriorly between the opening of the two bronchi 

this area is the most sensitive area of trachea which helps in cough reflex this can be seen in bronchoscopy.

NEUROVACULATURE

  • Sensory innervation from recurrent laryngeal nerve.
  • Blood supply from the inferior thyroid artery.
  • Venous drainage is brachiocephalic, azygos, and accessory hemiazygos veins.


BRONCHI

  • At the level of the sternal angle trachea bifurcates into right main bronchi and left main bronchi.
  • Each secondary bronchi supplies a lobe of the lung and give rise to several segmental bronchi.

STRUCTURE

  1. Right main bronchi: It is shorter and wider and descends more vertically than its left side.

  • This region is known to be higher at incidence of foreign particle inhalation.
  •         The right superior lobar bronchus arises before the right main bronchus enter the hilum.

    2.    Left main bronchus: It passes inferiorly to the arch of aorta and anteriorly to the thoracic aorta and esophagus in order to reach the hilum of the left lung.

  • Each secondary bronchi supplies a lobe of lung.
  • There are 3 right bronchi and 2 left bronchi
  • Lobar bronchi bifurcates into several segments.
  • Each of them supplies a bronchopulmonary segment.
Bronchopulmonary segments are subdivision of the lung lobes and they act as a functional units of the lungs
  • Structure of the bronchi is almost similar to the trachea but shape of cartilage will be different.
  • In the main bronchi, the cartilage rings will completely encircle the lumen.
  • Small lobar and segmental bronchi cartilage is found only in crescent shape

NEUROVASCULAR SUPPLY

Innervation: vagus nerve

Blood supply: bronchial artery

Venous drainage: Bronchial vein.

BRONCHIOLES 

The segmental bronchi undergoes the branching to from number of number airways.

STRUCTURE

The bronchioles are small and they doesn't have any cartilage or mucus secreting goblet cells.

ALVEOLI

These are tiny air filled pockets or air sac with thin walls.

This is a site for gaseous exchange in lungs

 


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