hello friends and welcome to my channel in this video we'll be learning about the anatomy of the lungs to begin with the lungs are a pair of respiratory organs situated in the thoracic cavity the right and left lungs are separated by a mediastinum which is a space in between the two lungs the lungs are spongy in texture in the young the lungs are gray or brown in color the right lung weighs about 700 grams and is about 50 to 100 grams heavier than the left lung there are 10 bronchopulmonary segments in each lung now let's learn about the features of the lungs each lung is conical in shape it has an apex at the upper end a base that rests on the diaphragm three borders that is anterior border posterior border that lies behind and an inferior border it has two surfaces coastal surface and medial surface coastal surface is the one that is seen outside and median is towards the medial side of the lung now this is a diagram of the medial surface of the left lung now here you can see that the medial surface is divided into two the vertebral part and the mediastinal part concising the important points under the introduction to the lungs the lungs are a pair of respiratory organs situated in the thoracic cavity each lung invaginates the corresponding pleural cavity the right and left lungs are separated by the mediastine the lungs are spongy in texture in the young the lungs are brown or grey in color the right lung weighs about 700 grams it is about 50 to 100 grams heavier than the left lungs there are 10 bronchopulmonary segments in each lung moving on to the features each lung is conical in shape it has an apex at the upper end base resting on the diaphragm three borders that is anterior posterior and inferior two surfaces postal and medial the medial surface is divided into vertebral and mediastinal parts now let's look at each of these features in detail first let's look at the epics the apex is blunt and lies above the level of the anterior end of the first strip now as you can see in this diagram here is the first strip here is the clavicle so the apex of the lung lies above the level of the anterior end of the first strip just about now this apex of the lung reaches nearly 2.5 centimeter above the medial one third of the clavicle just medial to the supraclavicular fossa now let's look at the base of the lung the base is semilunar and concave it rests on the diaphragm which separates the right lung from the right lobe of the liver and the left lung from the left lobe of the liver the fungus of the stomach as well as the spleen just to make it more clear here is the right lung here is the left lung here is the diaphragm that separates the right lung from the right lobe of the liver the left lung from the left lobe of the liver the fungus of the stomach and the spleen now let's look at the anterior borders of both the lungs in detail now it is very thin and shorter than the posterior border on the right side the anterior border is vertical as you can see right here the anterior border of the left lung shows a wide cardiac notch below the level of the fourth coastal cartilage the heart and pericardium are not covered by the lung in this region of the notch as you can see right here now the posterior border that lies behind it is thick and ill-defined it corresponds to the medial margins of the head of the ribs and it extends from the level of the seventh cervical spine to the tenth thoracic spine looking at the inferior border of the lung right here it separates the base of the lung from the coastal and the medial surfaces of the lung now let's look at the coastal surfaces of the lung it is large and convex it is in contact with the coastal pleura and overlying thoracic wall let's learn in detail about the medial surface of the lungs here is a diagram of the medial surface of the left lung now it is divided into a vertebral part and a mediastinal part that i had shown you earlier the vertebral part is also called the posterior part and the mediastinal part is also called the anterior part the vertebral part is related to the vertebral bodies the intervertebral discs the posterior intercostal vessels and the splanchnic nerves now the mediastinal part is related to the mediastinal septum and shows a cardiac impression hilum and a number of other impressions which differ on both the sites now concising the important points under the apex it is blunt and lies above the level of the anterior end of the first strip it reaches nearly 2.5 centimeters above the medial one-third of the clavicle just medial to the supraclavicular fossa looking at the features under the base it is semilunar and concave it rests on the diaphragm which separates the right lung from the right lobe of the liver and the left lung from the left lobe of the liver the fundus of the stomach and the spleen looking at the anterior border it is very thin and shorter than the posterior border on the right side it is vertical the anterior border of the left lung shows a wide cardiac notch below the level of the fourth coastal cartilage the heart and the pericardium are not covered by the lung in this region of the notch the posterior border is thick and ill-defined it corresponds to the medial margins of the head of the ribs it extends from the level of the seventh cervical spine to the tenth thoracic spine and finally the inferior border separates the base from the coastal and medial surfaces the coastal surface is large and convex it is in contact with the coastal pleura and overlying thoracic wall the medial surface is divided into posterior or vertebral part and an anterior or mediastinal part the vertebral part is related to vertebral bodies intervertebral discs posterior intercostal vessels and splanchnic nerves the mediastinal part is related to the mediastinal step septum and shows a cardiac impression hilum and a number of other impressions which differ on the two sides now let's learn about the fissures and the lobes of the lung the right lung is divided into three loops the upper middle and lower low by two fissures that is the oblique fissure and the horizontal fissure the left lung is divided into two lobes by the oblique fissure the oblique fissure cuts into the whole thickness of the lung except at the hilum in the right lung the horizontal fissure that you see right here extends from the anterior border up to the oblique fissure separating a wedge-shaped middle lobe from the upper lobe it runs horizontally at the level of the fourth coastal cartilage and meets the oblique fissure at the mid axillary line now the lingula that you see right here is a tongue shaped projection of the left lung below the cardiac notch concising the important points under the fissures and lobes of the lung the right lung is divided into three loops that is the upper middle and lower by two fissures that is the oblique and horizontal fissure the left lung is divided into two lobes by the oblique fissure the oblique fissure cuts into the whole thickness of the lung except at the hilum it passes obliquely downwards and forwards crossing the posterior border about six centimeter below the apex and the inferior border about 5 centimeter from the median plane in the right lung the horizontal fissure passes from the anterior border up to the oblique fissure and separates a wedge-shaped middle lobe from the upper lobe it runs horizontally at the level of the fourth coastal cartilage and meets the oblique fissure in the mid axillary line lingula is the tongue shaped projection of the left lung below the cardiac notch now let's look at the surface marking of the lung the oblique fissure can be drawn by joining a point two centimeter lateral to the third thoracic spine a point in the fifth rib in the mid axillary line and a point on the sixth coastal cartilage 7.5 centimeters from the median plane the horizontal fissure is represented by a line joining the point on the anterior border of the right lung at the level of fourth coastal cartilage and a second point on the fifth rib in the mid axillary length now let's look at the root of the lung so this is a diagram of the mediastinal or the medial surface of the right lung now the root of the lung is a short broad pedicle or a collection of structures which connect the medial surface of the lung to the media steiner it is formed by structures which either enter or come out of the lung at the high level to make the point more clear the root of the lung comprises the structures which connect the medial surface of the lung to the mediastinum and hilum is the area where the structures enter and come out from the lung the roots of the lung lie opposite to the bodies of the fifth sixth and seventh thoracic vertebrae next let's learn about the contents of the root of the love before we look at the contents of the root of the lung let me tell you an easy way to remember it now firstly when we think about the contents we can think of the bronchus that will be present then the arteries that supply the lung the veins the nerve plexuses the lymphatics and finally the areolar tissue so we have six things six contents that we will be discussing about first is the bronchus the arteries veins the lymphatics the nerve plexuses and the areolar tissue so firstly let us look at the bronchus so here is the left lung here is the right lung and here on the left lung we can see the principal bronchus on the right lung we can see the high partarian and eparterial bronchus apartheid bronchus is above and high part areal bronchus is below nextly looking at the arteries and veins we have pulmonary artery and pulmonary vein as well as bronchial artery and bronchi so here is one pulmonary artery on each side of the root of the lung right here and here is two pulmonary veins of the left side and two pulmonary veins of the right side now looking at the bronchial arteries we have one on the right side and two on the left side looking at the bronchial veins it is present on each side now looking at the nerves there is a presence of anterior and posterior pulmonary plexus of nerves looking at the lymphatics we have two types first is the lymphatics of the lung and second is the bronchopulmonary lymph nodes so here is the highla lymph node that you see right here and right here and finally we have areolar tissue now concising the important points under the root of the lung it is a short broad pedicle which connects the medial surface of the lung to the mediastinum it is formed by structures which either enter or come out of the lung at the height the roots of the lungs lie opposite the bodies of fifth sixth and seventh thoracic vertebrae now let's look at the contents the root is made up of the following structures that is a principal bronchus on the left side one pulmonary artery two pulmonary veins bronchial arteries one on the right and two on the left the bronchial veins the anterior and posterior pulmonary plexus of nerves the lymphatics of the lung the bronchopulmonary lymph nodes and the areolar tissue so we have the bronchus the pulmonary artery pulmonary vein bronchial artery bronchial vein the pulmonary plexus of nerves the lymphatics of the lung and the lymph nodes and finally the areolar tissue now let's learn about the arrangement of the structures in the root of the lung now here is the root of the right lung and here is the root of the left lung this is the anterior aspect of the right side this is the posterior aspect of the right side superior and inferior this is the anterior aspect of the left side the posterior aspect of the left side superior and inferior so the arrangement of structures in the root of the lung from anterior to posterior is similar on both the sides that is we have the superior pulmonary vein the pulmonary artery and the bronchus similarly from here from the anterior posterior side we have the superior pulmonary vein the pulmonary artery and the bronchus from above to downwards it is different on both the sides on the right side the structures that we see from above to downwards are the ep arterial bronchus right here the pulmonary artery and the inferior pulmonary vein on the left side the structures that we see from above downwards are the pulmonary artery the bronchus and the inferior pulmonary vein now concising the important points under the arrangement of the structures in the root from anterior to posterior it is similar on the two sides it is a superior pulmonary vein pulmonary artery and bronchus from above downwards it is different on the two sides the on the right side we have the ep arterial bronchus the pulmonary artery the inferior pulmonary v on the left side we have the pulmonary artery the bronchus and the inferior pulmonary vein now let's look at the relations of the root the relations that are common on two sides are the phrenic nerve the pericardiophrenic vessels and the anterior pulmonary plexus that you see right here and right here on the right side of the root of the lung there is the superior vena cava and parts of the right atrium in the posterior relations of the root of the lung we have certain common structures one is the vagus nerve that cannot be seen in this diagram and second is the posterior pulmonary plexus right here and right here and in these diagrams we can see that here is the root of the lung and here is the posterior relation of the left lung and posterior relation of the right lung so here we can see that there is the descending thoracic iota right here on the left side looking at the superior relations on the right side we can see the terminal part of the azygos vein and on the left side we can see the arch of the iota now the inferior relation of the root of the lung is the pulmonary ligament that you see right here and right here concising the important points under the relations of the root of the lung the anterior relations that is common on two sides are the phrenic nerve the pericardiophenic vessels and the anterior pulmonary plexus on the right side we have the superior vena cava and part of the right atrium looking at the posterior relations first is the relations that are common on the two sides that is the vagus nerve and posterior pulmonary plexus on the left side it is the descending thoracic iota looking at the superior relations we have on the right side the terminal part of the azygos vein and on the left side we have the arch of the iota inferior relations include the pulmonary ligament now let's look at the blood supply of the lung so in this diagram we can see the trachea and the esophagus the bronchial arteries that you see right here and here supply nutrition to the bronchial tree and to the pulmonary tissue these are small arteries that vary in number size and origin now on the right side there is one bronchial artery that is the right bronchial artery which arises from the third posterior intercostal artery now on the left side there are two bronchial arteries as you can see right here both of which arise from the descending thoracic iota now deoxygenated blood is brought to the lungs by two pulmonary arteries here is the right pulmonary artery and here is the left pulmonary artery and oxygenated blood is carried to the heart by four pulmonary veins here is the left superior pulmonary vein here is the left inferior pulmonary vein here is the right inferior pulmonary vein and there is a right superior pulmonary vein as well now let's look at the venous drainage of the lungs the venous blood from the first and second divisions of the bronchi are usually carried by bronchial weights usually there are two bronchial veins on each side the right bronchial veins drain into the azygos vein that you see right here the left bronchial veins drain into the hemi azygos vein that you see right here the greater part of the venous blood from the lungs is drained by the pulmonary weights concising the important points under the arterial supply of the lung the bronchial artery supply nutrition to the bronchial tree and the pulmonary tissue on the right side there is one bronchial artery which arises from the third right posterior intercostal artery on the left side there are two bronchial arteries both of which arise from the descending thoracic iota deoxygenated blood is brought to the lungs by the two pulmonary arteries and oxygenated blood is returned to the heart by four pulmonary veins looking at the venous drainage of the lungs the venous blood from the first and the second divisions of the bronchi is carried by bronchial veins the right bronchial veins drain into the azygos vein and left bronchial vein drains in to the hemiazygos v the greater part of the venous blood from the lungs is drained by the pulmonary veins looking at the lymphatic drainage superficial vessels drain the peripheral lung tissue and deep lymphatics frame the bronchial tree the pulmonary veins and connective tissue septa looking at the nerve supply parasympathetic nerves are derived from the vagus sympathetic nerves are derived from the second to fifth sympathetic ganglion now let's learn about the bronchial tree the trachya that you see right here divides at the level of the lower border of the fourth thoracic vertebrae into two primary principal bronchi one for each lung so here is the right principle bronchus and here is the left principle bronchus the right principle bronchus is 2.5 centimeter long it is shorter wider and more in line with the trachea than the left principal bronchus the left principal bronchus is 5 centimeters it is longer narrower and more oblique than the right bronchus the right bronchus makes an angle of 25 degree with the tracheal bifurcation while the left bronchus makes an angle of 45 degree with the trachea now each principle bronchus enters the lung through the hilum and divides into secondary low bar bronchi one for each lobe of the lung so for the right lung we learn that there are three lobes so there will be three low bar bronchi one two and three and for the left lung there are two lobes so there will be two low bar bronchi one and two now each low bar bronchus divides into tertiary or segmental bronchi one for each bronchopulmonary segment since there are 10 bronchopulmonary segments in each lung there are 10 segmental bronchi for each lung the segmental bronchi divide repeatedly to form very small branches called the terminal bronchus and still smaller branches than that are called respiratory bronchioles each respiratory bronchiole aerates a small part of the lung known as the pulmonary unit now as you can see in this diagram here is a branch of a terminal bronchiole and it ends in respiratory bronchiole which generates a small part of the lung known as a pulmonary unit now the respiratory bronchiole ends in microscopic passages which are termed as alveolar ducts that you can see right here atria right here the air saccules and pulmonary alveoli now gaseous exchange takes place in these alveoli these are the small alveoli concising the important points under the bronchial tree the trachea divides at the level of the lower border of the fourth thoracic vertebra into two primary principal bronchi one for each lung the right principle bronchus is 2.5 centimeters long it is shorter wider and more in line with the trachea than the left principal bronchus the left principal bronchus is 5 centimeter it is longer narrower and more oblique than the right bronchus the right bronchus makes an angle of 25 degrees with the truck kill bifurcation the left bronchus makes an angle of 45 degrees with the tokyo each principal bronchus enters the lung through the hilum and divides into secondary low bar bronchi one for each lobe of the lungs the right side has three lobar bronchi and left side has two loba bronchi each loba bronchus divides into tertiary or segmental bronchi one for each bronchopulmonary segment so the right side has ten bronch tertiary or segmental bronchi and the left side has 10 tertiary or segmental bronchi now the segmental bronchi divide repeatedly to form very small branches called the terminal bronchioles still smaller branches are called the respiratory bronchioles and each respiratory bronchiole aerates a small part of the lung known as the pulmonary unit now let's learn about bronchopulmonary segments now let's look at the definition of bronchopulmonary segments these are well defined well-defined anatomical functional and surgical sectors of the lung each one of these bronchopulmonary segments is aerated by a tertiary or segmental bronchus and each segment is pyramidal in shape with its apex directed towards the root of the lung each of these segments has a segmental bronchus segmental artery autonomic nerves and lymph vessels now let's learn the names of each of these bronchopulmonary segments in the left lung and the right lung so first let's look at the right lung we already learned that the right lung has three lobes the upper lobe the middle low and the lower low so let's look at the segments in the upper lobe so before i tell you about the segments let me tell you that this diagram is a lateral view of the lung so the first segment is called the epical segment the second is the posterior segment and the third is the anterior segment looking at the middle loop we have the lateral segment and the medial segment looking at the lower lobe we have the superior segment we have the anterior and medial basal segments the lateral basal segment and finally the posterior basal segment now let us look at the segments in the left lung we already learned that there are two lobes the upper and the lower low so in the upper lobe we have an upper division and a lower division so in the upper division we can see three segments first is the apical segment second is the posterior segment and third is the anterior segment in the lower division we can see the superior lingula segment and the inferior lingula segment finally in the lower lobe we have the superior segment the anterior basal segment the medial basal segment the lateral basal segment and the posterior basal segment concising the important points are the bronchopulmonary segments these are well-defined anatomic functional and surgical sectors of the lung each one is aerated by a tertiary or segmental bronchus each segment is pyramidal in shape with its apex directed towards the root of the lung now let's learn about the right lung the lobes and the segments so the upper lobe of the right lung has three segments that is epical posterior and anterior the middle lobe has two segments there is a lateral and medial segment and the lower lobe has superior medial basal anterior basal lateral basal and posterior basal segments looking at the segments of the left lung the upper lobe of the left lung is further divided into upper division and a lower division the upper division has epical segment posterior and anterior segment the lower division has superior lingual and inferior lingual segment so the lower lobe of the left lung has superior segment medial basal anterior basal lateral basal and posterior basal segments i hope you found this video helpful to get the notes of lungs as well as other topics of anatomy physiology biomechanics psychology pathology and pharmacology visit my instagram page the link to which is given in the description below to get updates on my latest videos click on the subscribe button to get notifications tap on the bell icon thank you for watching