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 4 6 6

Parietal Pleura Cervical 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 pleura: lines, the back of the: Sternum, Ribs & costal cartilages, Intercostal spaces & Sides of vertebral bodies

Parietal Pleura Mediastinal pleura: covers the mediastinum. At the hilum, it is reflected on to the vessels and bronchi, and continuous with the visceral pleura. Diaphragmatic pleura: 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.

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. Pleural 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: Intercostal arteries. Internal thoracic artery. 3. Musculo-phrenic artery. Visceral Pleura: Bronchial arteries.  

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