THORAX

TRACHEA , BRONCHI & LUNGS

OUTLINE

• TRACHEA

• BRONCHI

• LUNGS & LUNG VESSELS

• CLINCAL CORRELATES

Learning objective

• By the end of this lecture, students should be able to:

• Know the anatomy of the trachea and their anatomical relations.

• Know the anatomy of the bronchi, anatomical relations and their differences.

• Know the anatomy of the lungs, anatomical relations and their differences.

• Have the knowledge of the lung vessels and their clinical importance

• Understanding the clinical correlates.

TRACHEA

• It begins at the inferior border of the cricoid cartilage (C6) as a continuation of the larynx

• It is about 12cm in length and nearly 2.5cm in diameter. • It ends by bifurcating into the right and left main stem

bronchi at the level of the sternal angle of Louis (T4/5) • It has 15–20 U-shaped incomplete hyaline cartilaginous rings

that open posteriorly toward the esophagus and prevent the trachea from collapsing.

• The carina of the last tracheal cartilage lies at the level of the sternal angle and forms a keel-like ridge separating the openings of the right and left main bronchi.

• Subject to compression by an aortic arch aneurysm, a goiter, or thyroid tumors, causing dyspnea.

• It lies partly in the neck and partly in the thorax.

TRACHEA:Cervical Relations

• Anteriorly— the isthmus of thyroid gland, inferior thyroid veins, sternohyoid and sternothyroid muscles;

• Laterally—the lobes of thyroid gland and the common carotid artery;

• Posteriorly—the oesophagus with the recurrent laryngeal nerve lying in the groove between oesophagus and trachea

TRACHEA ANTERIOR RELATIONS

TRACHEA-Thoracic Relations

• In the superior mediastinum its relations are:

• Anteriorly—commencement of the brachiocephalic (innominate) artery and left carotid artery, both arising from the arch of the aorta, the left brachiocephalic (innominate) vein, and the thymus;

• Posteriorly—oesophagus and left recurrent laryngeal nerve;

• Left— arch of the aorta, left common carotid and left subclavian arteries, left recurrent laryngeal nerve and pleura;

• Right—vagus, azygos vein and pleura

BRONCHI

• Right Main (Primary) Bronchus

• Left Main (Primary) Bronchus

Right Main (Primary) Bronchus

• Is shorter, wider, and more vertical than the left main bronchus; therefore, prone to more foreign bodies to enter through the trachea and lodge in this bronchus or inferior lobar bronchus.

• It is about 2.5cm long and passes directly to the root of the lung at T5 • Before joining the lung it gives off its upper lobe branch, and then

passes below the pulmonary artery to enter the hilum of the lung. • It divides into three lobar or secondary (superior, middle, and inferior)

bronchi and finally into 10 segmental bronchi • The right superior lobar (secondary) bronchus is known as the

eparterial (above the artery) bronchus because it passes above the level of the pulmonary artery. All others are the hyparterial bronchi.

• It has two important relations: the azygos vein, which arches over it from behind to reach the superior vena cava, and the pulmonary artery which lies first below and then anterior to it.

Left Main (Primary) Bronchus

• It is nearly 5cm long and passes downwards runs inferolaterally inferior to the arch of the aorta, crosses anterior to the esophagus and thoracic aorta

• Divides into two lobar or secondary bronchi, the upper and lower, and finally into 8 to 10 segmental bronchi. Unlike the right, it gives off no branches until it enters the hilum of the lung

• Is also crossed superiorly by the arch of the aorta over its proximal part and by the left pulmonary artery over its distal part.

• Dilates its lumen by sympathetic nerves and constricts by parasympathetic stimulation.

LUNGS • Essential organs of respiration and are attached

to the heart and trachea by their roots and the pulmonary ligaments.

• Each lung is conical in shape, blunt apex which reaches above the sternal end of the 1st rib, a concave base overlying the diaphragm, an extensive costovertebral surface moulded to the form of the chest wall and a mediastinal surface which is concave to accommodate the pericardium.

RT & LT LUNGS

TRACING OF A LT & RT OBLIQUE RADIOGRAPH OF THE CHEST.

RIGHT LUNG

• Apex projects into the neck and a concave base sits on the diaphragm. • Larger and heavier than the left lung, shorter and wider because of the higher

right dome of the diaphragm and the inclination of the heart to the left. • Divided into upper, middle, and lower lobes by the oblique and horizontal

fissures • Receives a single bronchial artery • Oblique fissure usually begins at the head of the 5th rib and follows roughly the

line of the 6th rib • Horizontal fissure runs from the oblique fissure in the midaxillary line at the 6th

rib level and extends forward to the 4th costal cartilage level. • Has 3 lobar (secondary) bronchi and 10 segmental (tertiary) bronchi. • Has grooves for various structures (e.g., SVC, arch of azygos vein, esophagus).

LEFT LUNG

• Divided into upper and lower lobes by an oblique fissure

that follows the line of the 6th rib, is usually more vertical in the left lung than in the right lung

• Receives two bronchial arteries. • Contains the lingula, a tongue-shaped portion of the upper

lobe that corresponds to the middle lobe of the right lung. • Contains a cardiac impression, a cardiac notch • Grooves for various structures (e.g., aortic arch, descending

aorta, left subclavian artery). • Has 2 lobar (secondary) bronchi and 8 to 10 segmental

bronchi.

BLOOD SUPPLY

BRONCHIAL ARTERIES & VEINS

LUNG BLOOD SUPPLY

• Pulmonary Trunk

• Left Pulmonary Artery

• Right Pulmonary Artery

• Pulmonary Veins

LUNG NERVE SUPPLY • Pulmonary Plexus

• Vagus- parasympathetic

• Sympathetic trunk-sympathetic

• Cardiac plexus.

• Divided into the anterior pulmonary plexus & posterior pulmonary plexus

• sympathetic nerve fibers that dilate the lumina of the bronchi and constrict the pulmonary vessels

• parasympathetic fibers constrict the lumina, dilate the pulmonary vessels, and increase glandular secretion.

• Phrenic Nerve

LYMPHATIC DRAINAGE

• Lymphatics of the lung drain centripetally

• Bronchopulmonary lymph nodes in the hilum, pass to the tracheobronchial nodes at the bifurcation of the trachea

• Thence to the paratracheal nodes and the mediastinal lymph trunks to drain usually directly into the brachiocephalic veins or, rarely, indirectly via the thoracic or right lymphatic duct.

CLINICAL CORRELATES-LUNG & BRONCHI

• Chronic obstructive pulmonary disease (COPD)- a group of lung diseases associated with chronic obstruction of airflow through the airways and lungs.

• Most common forms: Chronic bronchitis and emphysema. Asthma, Bronchiectasis

• Symptoms include chronic cough, difficulty in breathing, chronic sputum production, and wheezing.

• Treatment -bronchodilators and glucocorticoids.

PLEURA

• Pleurisy (pleuritis) is an inflammation of the pleura with exudation (escape of fluid from blood vessels) into its cavity

• Pneumothorax is an accumulation of air in the pleural cavity Major symptoms are chest pain and dyspnea (shortness of breath). Treated by draining the pleural air collection by simple aspiration using an intravenous catheter or chest tube thoracostomy.

• Pleural effusion is an abnormal accumulation of excess fl uid in the pleural space.

• Thoracentesis (pleuracentesis or pleural tap) is a surgical puncture of the thoracic wall into the pleural cavity for aspiration of fluid- hydrothorax (water), a hemothorax (blood), a chylothorax (lymph), and a pyothorax (pus).

LUNGS

• Pneumonia (pneumonitis) is an inflammation of the lungs, which is of bacterial and viral origin. Symptoms are usually cough, fever, sputum production, chest pain, and dyspnea. Treatment -administering antibiotics for initial therapy.

• TB is an infectious lung disease caused by the bacterium Mycobacterium tuberculosis. Symptoms- cough, fever, sweats, tiredness, and emaciation. Spread is by inhaled coughing.

• Pancoast’s or superior pulmonary sulcus tumor is a malignant neoplasm of the lung apex and causes Pancoast’s syndrome,

Text & Image Sources: Acknowledgement

• Drake, Vagi & Mitchell. 2015. Gray’s Anatomy for Students 3rd Ed; Churchill Livingstone Elsevier Inc. Philadelphia

• Agur & Dalley II. 2013. Grant’s Atlas of Anatomy, 13th Ed; Lippincott Williams & Wilkins. Philadelphia.

• Sinnatamby C.S. 2011. Last’s Anatomy Regional & Applied Anatomy, 12th Ed; Churchill Livingstone Elsevier Inc. Philadelphia

• Moore, Dally II & Agur. 2014. Lippincott Williams & Wilkins. Philadelphia.

• Chung & Chung. 2012. BRS Gross Anatomy, 7th Ed; Lippincott Williams & Wilkins. Philadelphia.

• Harold Ellis; 2006. Clinical Aantomy 11th Ed; Black Publishing

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