Trachea, Bronchial Tree & Pleura

Dr. Sama ul Haque

Dr Rania Gabr

Objectives

Discuss the anatomical structure of the trachea with its relations.

Define the term bronchial tree.

Describe bronchopulmonary segments.

Explain pleura.

Lower Respiratory Tract

Trachea

Bronchi

Bronchial Tree

Terminal Bronchioles

Respiratory Bronchioles

Alveolar Sacs

Lungs

Conducting zone of lower Respiratory Tract

Trachea

Definition:

It is a fibro-muscular tube (Windpipe) 10 cm long

containing incomplete cartilaginous rings.

Continuation of the Larynx.

Posterior part of tube lined by trachealis muscle.

Anterior and lateral walls of the trachea supported

by 16 to 20 C-shaped tracheal cartilages.

Trachea

Cartilage rings reinforce and provide rigidity to

the tracheal wall to ensure that the trachea remains

open at all times.

Beginning: At the lower border of the cricoid

cartilage (at the level of C 6).

It begins in the midline and terminates slightly to

the right of the midline.

Trachea

Termination: At the level T4 (sternal angle),

the trachea bifurcates into two smaller tubes at the

level opposite T4-T5, called the CARENA

the right and left primary bronchi are the result of

the bifurcation.

Each primary bronchus projects laterally towards

each lung.

Trachea

Blood supply:

a. Inferior thyroid arteries.

b. Bronchial arteries from the descending thoracic aorta (left side).

c. Right superior intercostal artery (right side).

- It is drained by the inferior thyroid veins.

Nerve supply:

Sympathetic: Sympathetic trunk.

Parasympathetic: Vagi nerves.

Bronchi

Right primary bronchus is shorter, wider, and

more vertically oriented than the left primary

bronchus.

Foreign particles are more likely to lodge in the

right primary bronchus.

Bronchial tree

A highly branched system of air-conducting

passages that originate from the left and right

primary bronchi.

Progressively branch into narrower tubes as they

diverge throughout the lungs before terminating in

terminal bronchioles.

Bronchial tree

The primary bronchi enter the hilus of each lung together

with the pulmonary vessels, lymphatic vessels, and

nerves.

Each primary bronchus branches into several secondary

bronchi (or lobar bronchi).

The left lung has two secondary bronchi. The right lung

has three secondary bronchi.

They further divide into tertiary bronchi.

Bronchial Tree

Each tertiary bronchus is

called a segmental bronchus

because it supplies a part of

the lung called a

bronchopulmonary segment.

Secondary bronchi tertiary

bronchi bronchioles

terminal bronchioles

Thoracic Cavity

The thoracic cavity consists of:

I. Lung and its pleura: on each side.

II. Mediastinum:

In the middle part.

The mediastinum contains the heart, great vessels, and other structures.

Pleura

Definition:

-It is a closed serous sac which is invaginated by the lung from its medial side.

Layers:

I. Visceral layer ----------------- Lines the surfaces and fissures of the lung.

II. Parietal layer ---------------- Lines the thoracic wall and other structures.

SUFACE ANATOMY OF PLEURA

6

4

6

Parietal Pleura

• Cervical PleuraCervical Pleura:• Projects up into the

neck about one inch above the medial1/3rd of clavicle.

• It lines the under surface of the suprapleural membrane.

• Costal pleuraCostal pleura::• lines, the back of the:• Sternum,• Ribs & costal

cartilages,• Intercostal spaces & • Sides of vertebral

bodies

Parietal Pleura

Mediastinal Mediastinal pleurapleura: covers the mediastinum.

At the hilum, it is reflected on to the vessels and bronchi, and continuous with the visceral pleura.

Diaphragmatic Diaphragmatic pleurapleura: : covers the thoracic (upper) surface of the diaphragm.

Pleural Recesses

Costodiaphragmatic: Slit like space

between costal and diaphragmatic pleurae, along the inferior border of the lung which enters through it in deep inspiration.

Costomediastinal: Slit like space

between costal and mediastinal pleurae, along the anterior border of the lung which enters through it in deep inspiration.

Pleural Cavities

• The potential space between the serous

membrane layers is a pleural cavity.

• The pleural membranes produce a thin, serous

pleural fluid that circulates in the pleural

cavity and acts as a lubricant, ensuring

minimal friction during breathing.

Pleural Pleural Effusion Effusion

It is an abnormal accumulation of pleural fluid about 300 ml, in the Costodiaphragmatic pleural recess , (normally 5-10 ml fluid)

Causes: inflammation, TB, congestive heart disease and malignancy.

The lung is compressed & the bronchi are narrowed.

Auscultation would reveal only faint & decreased breathing sounds over compressed or collapsed lung lobe.

Dullness on percussion over the effusion.

Nerve supply of the pleura

Parietal pleura:1. Costal pleura and peripheral diaphragmatic pleura:

Intercostal nerves

2. Mediastinal and central diaphragmatic pleura :

Phrenic nerves

3. Diaphragmatic pleura is supplied over the domes by phrenic nerves, around the periphery by lower 6 intercostal nerves.

Visceral pleura:

Not sensitive (has autonomic nerve supply).

  

 Arterial supply of the pleura

Partial Pleura:

1. Intercostal arteries.

2. Internal thoracic artery.

3. Musculo-phrenic artery.

Visceral Pleura:

Bronchial arteries. 

Thank you