Lungs/Pulmones

Lungs/pulmones

©NotesMed.com Lungs/pulmones

• Principal organs of respiration. • The two lungs (right and left) are situated in the thoracic cavity, one on either side of the mediastinum enclosed in the pleural sac. • Each lung is large conical/pyramidal shaped with its base resting on the diaphragm and its apex extending into the root of the neck. • The right lung is larger and heavier than the left lung. • The right lung weighs about 700 g and left lung 650 g. • The right lung has three lobes and the left lung has two lobes. • The lobes are separated by deep prominent fissures on the surface of the lung and are supplied by two lobar bronchi.

• Apex. • Base. • Three borders – Anterior – Posterior – Inferior • Two surfaces – Costal – Medial

©NotesMed.com ©NotesMed.com Anatomical position and side determination • Its conical end (apex) is directed upwards and its broader end (base) is directed downwards. • Its convex surface (costal surface) is directed outwards and its flat medial surface presenting hilum is directed inwards. • Its thin margin (anterior margin) should face forwards and its rounded border (posterior border) should face backwards.

©NotesMed.com Apex • The apex is rounded/blunt superior end of the lung. • Extends into the root of the neck about 3 cm superior to the anterior end of the 1st rib and 2.5 cm above the medial 1/3rd of the clavicle. • Covered by cervical pleura and suprapleural membrane. • Covered with cervical pleura and strengthened externally by Sibson’s fascia. Relations: • Anterior: – Subclavian artery. – Internal thoracic artery. – Scalenus anterior. • Posterior: – Neck of 1st rib and structures in front of it, e.g., • Ventral ramus of first thoracic nerve, • First posterior intercostal artery, • First posterior intercostal vein • Sympathetic chain.

©NotesMed.com ©NotesMed.com Base • lower semilunar concave surface. • Rests on the dome of the diaphragm, hence it is also sometimes called diaphragmatic surface. • Relations • On the right side, – The lung is separated from the liver by the right dome of the diaphragm. • On the left side, – The left lung is separated from the spleen and fundus of stomach by the left dome of the diaphragm.

©NotesMed.com Border • Anterior border: – Thin and shorter than the posterior border. – The anterior border of right lung is vertical. – The anterior border of left lung presents a wide cardiac notch, which is occupied by the heart and pericardium. – In this region, the heart and pericardium is uncovered by the lung. Hence this region is responsible for an area of superficial cardiac dullness. Below the cardiac notch, it presents a tongue- shaped projection called lingula. • Posterior border: – Thick and rounded. – Extends from spine of C7 vertebra to the spine of T10 vertebra. • Inferior border: – Semilunar in shape and separates the costal and medial surfaces.

©NotesMed.com ©NotesMed.com Surfaces • Costal Surface – Large, smooth, and convex. – Covered by the costal pleura and endothoracic fascia. • Relations: – Related to the lateral thoracic wall. – The number of ribs related to this surface is as follows: • Upper 6 ribs in midclavicular line. • Upper 8 ribs in midaxillary line. • Upper 10 ribs in scapular line. • (In embalmed and hardened lung, the costal surface presents impressions of the ribs.)

©NotesMed.com ©NotesMed.com Medial Surface

• Small posterior vertebral part. • Large anterior mediastinal part. Relations: • vertebral part: – Related to the vertebral column, – Posterior intercostal vessels, and greater and lesser splanchnic nerves.

©NotesMed.com Medial Surface • Mediastinal part presents a hilum, and it is related to mediastinal structures such as heart, great blood vessels, and nerves.

©NotesMed.com Medial surface

Groove for trachea

©NotesMed.com Right Mediastinal Surface Left Mediastinal Surface

©NotesMed.com Lobes and fissures

• The right lung is divided into three lobes: – Superior – Middle and – Inferior – Separated by two fissures • an oblique fissure and a horizontal fissure. • The left lung is divided into two lobes: – Superior – Inferior – Separated by an oblique fissure.

©NotesMed.com Root of the lung

• A short broad pedicle connecting the medial surface of the lung with the mediastinum. • The root of lung lies opposite the bodies of T5, T6, and T7 vertebrae. • The hilum is the area on the mediastinal surface of the lung through which structures enter or leave the lung. • The root of lung is surrounded by a tubular sheath derived from the mediastinal pleura.

©NotesMed.com ©NotesMed.com Components of root of lung

• Principal bronchus in the left lung, and eparterial and hyparterial bronchi in the right lung. • Pulmonary artery. • Pulmonary veins (two in number). • Bronchial arteries (one on the right side and two on the left side). • Bronchial veins. • Lymphatics of the lung. • Anterior and posterior pulmonary plexuses of the nerves.

©NotesMed.com Arrangement of structures in the root • From before backwards (it is more or less similar on two sides): – Pulmonary vein (superior) – Pulmonary artery – Bronchus (left principal bronchus on the left side, and eparterial, and hyparterial bronchus on the right side). • From above downwards (it differs on two sides): Right side Left side Eparterial bronchus Pulmonary artery Pulmonary artery Left principal bronchus Hyparterial bronchus Inferior pulmonary vein Inferior pulmonary vein ©NotesMed.com From anterior to posterior

Lower Left P

©NotesMed.com Right side BABV

Upper Right PV

©NotesMed.com Left side ABV

Lower Left

©NotesMed.com Relations of the root of the lung • Anterior: – Phrenic nerve. – Anterior pulmonary plexus. – Superior vena cava (on right side only). • Posterior: – Vagus nerve. – Posterior pulmonary plexus. – Descending thoracic aorta (on left side only). • Superior: – Arch of azygos vein (on right side only). – Arch of aorta (on left side only). • Inferior: – Pulmonary ligament.

©NotesMed.com Bronchopulmonary segments The bronchopulmonary segments are well-defined, wedge- shaped sectors of the lung, which are aerated by tertiary (segmental) bronchi. Right lung Left lung • Superior: • Superior: – Apical – Apical – Posterior – Posterior – Anterior – Anterior • Middle: – Superior lingular – Lateral – Inferior lingular – Medial • Inferior • Inferior: – Superior (apical) – Superior (apical) – Medial basal – Medial basal – Anterior basal – Anterior basal – Lateral basal – Lateral basal – Posterior basal – Posterior basal ©NotesMed.com ©NotesMed.com ©NotesMed.com ©NotesMed.com Bronchopulmonary segment • Conical and apex towards the lung root. • Largest subdivision of a lobe of the lungs. • Separated by connective tissue septa. • Supplied by tertiary bronchus and tertiary branch of pulmonary artery. • Surgically resectable.

©NotesMed.com Characteristic features • It is a subdivision of the lobe of the lung. • It is pyramidal in shape with apex directed towards the hilum and base towards the surface of the lung. • It is surrounded by the connective tissue. • It is aerated by the segmental (tertiary) bronchus. • Each segment has its own artery, a segmental branch of the pulmonary artery. • Each segment has its own lymphatic drainage and autonomic supply.

©NotesMed.com Blood Supply

• Functionally two distinctive circulatory pathways Pulmonary Vessels – Pulmonary artery – Pulmonary vein • Bronchial Vessels – Bronchial artery – Bronchial vein

©NotesMed.com Blood Supply

Bronchial Arteries • Left – Two – From Descending Thoracic Aorta • Right – One – From right 3rd Posterior Intercostal artery or upper left BA

©NotesMed.com Venous drainage • Superficial set: – Two bronchial veins on each lung • Drains blood from visceral pleura, extra-pulmonary bronchi, hilar lymph node and terminate on the • Right lung: into Azygos vein. • Left lung: into left superior intercostal or accessory hemiazygous vein. • Deep set: – Drains blood from intrapulmonary bronchi and bronchiole. – Terminate into pulmonary vein or directly to Left Atrium.

• Consists of superficial and deep sets • Superficial set: – Ramify beneath the visceral pleura from peripheral lung tissue. • Deep set: – Ramify around the intrapulmonary bronchi and bronchioles and around the pulmonary vessels. – Drains lymph from bronchial tree, pulmonary vessels and connective tissue septa. • Both sets – bronchopulmonary node- Superior & Inferior tracheobronchial Lymph node- Paratracheal Lymph node– bronchomediastinal lymph trunk- Junction of respective inferior jugular vein and superior vena cava through thoracic duct on the left side ad right Lymphatic duct on the right side.

• Pulmonary plexus is formed by – Parasympathatic fibers from vagus nerve – Sympathatic fibers from upper 4 or 5 thoracic ganglia of sympathatic trunk.

©NotesMed.com Pleura • The pleura-like peritoneum is a serous membrane lined by flattened epithelium (mesothelium). • The lining epithelium secretes a watery lubricant—the serous fluid. • Layers of the pleura: – Two layers: • Visceral pleura and • Parietal pleura. • Space between the two layers is called pleural cavity (vide supra).

• The visceral pleura completely covers the surface of the lung except at the hilum and along the attachment of the pulmonary ligament. • Extends into the depths of the fissures of the lungs. • Firmly adherent to the lung surface and cannot be separated from it.

©NotesMed.com Parietal Pleura • Thicker than the visceral pleura and lines the walls of the pulmonary cavity. • Subdivisions: – Costal pleura. – Diaphragmatic pleura. – Mediastinal pleura. – Cervical pleura.

©NotesMed.com Pulmonary ligament • The pleura surround the root of the lung similar to the cuff (sleeve) of the jacket around the wrist. • Extends down as a fold called pulmonary ligament. • The pulmonary ligament extends from the root of the lung as far down as the diaphragm between the lung and mediastinum. • The fold is filled with loose areolar tissue and contain few lymphatics.

©NotesMed.com Function of pulmonary ligament • Provides a dead space into which the pulmonary veins can expand during increased venous return as during exercise. • It allows the descent of the root of the ling with the descent of diaphragm during inspiration. As a result, the apex of lung comes down from the tough suprapleural membrane leaving an empty space below the membrane. Now the apex of the lung can expand into this empty space.

©NotesMed.com Recesses of the pleura • Areas of pleural reflection on to the diaphragm and mediastinum, the space between the parietal and visceral pleura is greatly expanded. These expanded regions of pleural cavity are called pleural recesses. • Pleural recesses serve as reserve spaces of pleural cavity for the lungs to expand during deep inspiration. – Costodiaphragmatic recesses (right and left). – Costomediastinal recesses (right and left).

• Arterial Supply: – Parietal : • Intercostal Artery • Internal Thoracic Artery • Musculophrenic Artery – Visceral: • Bronchial Artery • Venous Drainage: – Parietal : • Azygous Vein • Internal Thoracic Vein – Visceral: • Bronchial Vein. ©NotesMed.com Nerve supply

• Parietal: – Somatic nerves and is pain sensitive intercostal and phrenic nerve. • Visceral: – Supplied by autonomic nerves and is not pain sensitive.

• Pleuritis or pleurisy. • Pneumothorax . • Hydropneumothorax. • Hemothorax. • Empyema. • Pleural effusion.