bronchi

Bronchi (Bronchus) - Bronchial Tree

Trachea divides at the level of lower border of 4th thoracic vertebra into two primary principal bronchi, one for each lung that carry air from windpipe to lungs. Trachea and two primary bronchi termed as bronchial tree. 

Trachea divides into -

1. Right primary bronchi

2. Left primary bronchi

1. Primary Bronchi

A. Right primary bronchi 

Right main bronchus subdivides into three secondary bronchi (also known as lobar bronchi).

Length - 2.5cm long

It is shorter, wider, more verticle and more in line with trachea than the left primary bronchi.

Inhaled particle pass more frequently to right lungs.

With the result that infection are more common on the right side than the left.

It enters the right lung nearly opposite of 5th thoracic vertebra.

B. Left primary bronchi 

Left main bronchus divides into two secondary bronchi or lobar bronchi.

Length - 5cm long

It is longer, narrow and more oblique than right pulmonary bronchi.

It enters the root of left lung opposite to 6th thoracic vertebra.

2. Secondary Lobar Bronchi

Principal bronchi enters the lungs through hilum and divides into secondary bronchi.

Right lung has three lobar bronchi and left lung has two lobar bronchi.

3. Tertiary or Segmental Bronchi

Each lobar bronchi divides into 10 tertiary bronchi each lungs.

Bronchioles

Tertiary bronchi divided to form very small branches called terminal branchioles.

Terminal branchioles divided small branches are called respiratory branchioles.

Respiratory branchioles ends in microscopic passage from Alveoli ducts, alveolic sacs and alveoli.