Trachea and the bronchial tree
In this specimen we can see the divisions of the trachea and the bronchial tree. The Trachea divides into two principal bronchi ‚Äì right and left. The principal bronchus on right side divides into three secondary bronchi, one for each lobe (upper, middle and lower). The principal bronchus on left side divides into two secondary bronchi for the upper and lower lobes. We can also see the bronchopulmonary segments. There are 10 segments on each side.
The trachea (Latin, air vessel; also called the wind-pipe) is a 10-15 cm long tube situated in the lower part of the neck and superior mediastinum. Its upper under is continuous with the larynx at the level of C6 vertebra. It is made up of C-shaped cartilaginous rings (hyaline in nature and 16-20 in number) anteriorly. Posteriorly the gap is closed by a fibro-elastic membrane and contains trachealis muscle. At the level of the sternal angle (i,e, lower border of T4 vertebra) the trachea bifurcates into two principal bronchi.
The bronchial tree or the respiratory tree is a collective term used for the subdivisions of the primary bronchi into secondary and tertiary bronchi.
The bronchopulmonary segment is a structural and functional unit of the lung that is aerated by a tertiary bronchus. Each lung has 10 bronchopulmonary segments. Each segment is pyramidal in shape with its apex directed towards the root of the lung. Each segment has a segmental bronchus, segmental artery (pulmonary and bronchail), autonomic nerves and lymph vessels. The pulmonary veins are intersegmental in position. Surgical removal of the diseased bronchopulmonary ligament is called ‚Äúsegmental resection of lung‚Äù.