Lung Pleura – Clinical Anatomy and Physiology

hello in this video we're going to talk about the lung pleura this is a clinical Anatomy video let's begin by reviewing the respiratory tract briefly starting from the larynx here goes down to the trachea chipiya bifurcates into the primary bronchi which then enters the right lung and the left lung behind the respiratory tract is the esophagus which then leads to the stomach below the diaphragm each lung is enveloped or enclosed by a sac which consists of a continuous serous membrane this is the pleura and the pleura will form the pleural cavity so here you have the right lung pleura and you have the left lung pleura you can think of the lung pleura like the pericardium of the hot like the pericardium it's a sac where the lungs sit here is a diaphragm which is an important muscle for respiration together with the intercostal muscles and the serratus the hot sits here in the mediastinum the liver is in the right upper quadrant below the diaphragm let us now look at the pleura and see its relationship to the bones medial and anterior you will find here the manubrium the sternum and the xiphoid process the clavicle is on top and attaches to the manubrium here is the axilla your armpit area and here you have the ribs which protect your lungs and heart as shown you have 12 ribs numbered here in red some important anatomical landmarks if we draw a straight line in the middle of the clavicle we can call this the midclavicular line and here is your mid axillary line where the exilic is you draw a straight line down where your armpit is essentially on the side of your body these are landmarks which are good to know because you can tell where roughly the lung margins and the pleural margins are remember that each lung is enclosed in a pleural sac the pleural margins we are talking about here is the outermost pleura membrane called the parietal pleura and we'll talk about this more a bit later anyway as you can see at the mid clavicular point the lungs should end at about the sixth rib in this diagram it shows the seventh rib but let's just say it's the sixth rib the pleura margin is always two above this so it ends as shown at the eighth rib looking at the mid auxilary point you can see the lung margins ends at the eighth rib and the pleura margin which is two above this ends at the tenth rib let's now focus more on the lung pleura and why it is a sac which holds the lungs and why there are two pleural membranes even though it's actually one continuous membrane here is the part of the respiratory tract and the lungs here are the ribs here is ribs 8 and ribs 10 remember the lung margins at the mid-axillary is about the eighth rib before introducing the pleura membrane and the pleural cavity remember the roots of the hilum here because it is here where the continuous sheet of the lung pleura changes from what's called the parietal pleura to what's called the visceral pleura the parietal pleura in blue extends to the roots of the lung the hilum you can say or remember the plural membrane is a continuous sheet and it continues and then it continues and envelopes the lung this in orange now is known as the visceral pleura which essentially adheres to the lungs so again at the root of the hilum you have the parietal pleura which goes and attaches to the thoracic wall and at the root of the hilum is when it changes into the visceral pleura which envelopes the lungs so you can say that the visceral pleura and the parietal pleura meet at the root of the hilum and thus the pleura itself is a continuous serous membrane serous sheet and this continuous membrane or sheet is more like a sac where the lungs actually sit now because it is a sac in between the parietal and visceral pleura you have the pleural cavity or the pleural space in the pleural cavity you have pleural fluid the pleural fluid flows through the pleural cavity the pleural reflection is essentially a line where the pleura itself the plural membrane changes direction to complete this diagram really important the parietal pora in blue covers the superior surface of the diaphragm and moves with the diaphragm during respiration here is the mediastinum where the hot seats now let's cut a cross-section of this area of the thorax to better understand pleural membranes and the pleural reflections here is the posterior part of the thorax you can see the spine with the the vertebrae here are your primary bronchi which enters your lungs on the left and on the right remember you have in blue your parietal pleura which attaches to the thoracic wall surrounding the lung is the visceral pleura which is the continuation of the parietal pleura the changes in name and direction described is known as the pleural reflection in between the parietal and visceral pleura is the pleural cavity which contains the pleural fluid in front of the vertebra and behind the trachea is where the esophagus goes down next to the esophagus more so on the left side is the descending aorta the mediastinum can be divided into several compartments as you know one of which is the posterior compartment where we can find the esophagus the descending aorta and then you have the middle compartment of the mediastinal where we can find hot and then you have the anterior compartment which is the sternum now let us enjoy a posterior view of the body and let us now look at more body landmarks so we can again outline the lung margins and the lung pleura from the back looking at the back of the person here you can find the scapula the vertebral spine in front of the scapula and vertebrae you have the right and left lung and you also have the plural membrane coming off the thoracic vertebrae you have the ribs your ribs here is ribs 10 to 12 again if we draw a line down the middle of the scapula you can call this now the mid scapula line the long margins as you can see it finishes at about the tenth rib in the mid scapula line and the pleura finishes at about two above this which is rib number twelve again the mid-axillary line is the imaginary line running through where your exile is your armpit basically on your side let's take a closer look at this area here down the bottom and look at it in a bit more detail and the structures so here's your visceral pleura which covers the lungs here is the parietal pleura which is a continuation of the visceral pleura and attaches to the thoracic wall then here and here is the space in between which is called the pleural space or the pleural cavity now the parietal pleura in blue as I mentioned attaches to the thoracic wall and here the thoracic wall are your ribs in between the ribs are your intercostal muscles which hold the ribs in place and also assists in respiration from the most inner pipe inner layer of the intercostal muscles is the innermost intercostal then after that is the internal intercostals and then your external intercostals this area I'm drawing here can also be called the left costal diaphragmatic recess on a chest x-ray this area is called the left costophrenic angle now the left costophrenic angle is very useful to look at on me on a chest x-ray because clinically if there is blunting or if the edge is filled sort of this can signify pleural effusion the diaphragm attaches superiorly to the parietal pleura layer pleural fluid builds the pleural space and pleural fluid comes from the parietal pleural circulation which is the main source it also comes from the visceral pleura circulation from the lungs and also partly by from the peritoneal cavity of via small holes in the diaphragm now the pleura membrane in summary has many functions but two main ones firstly you can imagine because it touches to the lungs and the thoracic wall it actually allows for changes in lung shape during respiration and secondly the pleura prevents the lungs from collapsing maintaining positive transpulmonary pressure let's zoom into this area here where the parietal and visceral pleura are in close proximity and learn a bit more about the physiology of the you know the pleura itself so again here in orange is the visceral pleura and in blue is the parietal pleura in between the visceral and parietal pleura is the pleural cavity the visceral and parietal pleura is made up of mesothelial cells below the visceral and parietal pleura is the basement membrane the space below the visceral pleura is a visceral space which is also basically the lungs which contain the alveoli and the pulmonary capillaries ready for gas exchange the parietal space is also the thoracic wall you have systemic capillaries in this area you also have lymph vessels here called the parietal lymph vessels which drained the fluid from the pleural space interestingly as discussed the source of the pleural fluid is mainly from the parietal pleura from its systemic circulation there is also some fluid produced from the visceral pleura as well ultimately the fluid circulating through the pleural cavity will drain into the parietal lymphatics mainly and the parietal lymphatics is able to absorb 20 times more fluid than is normally formed which is kind of important especially if there's too much parietal fluid being produced the substances that are found in the parietal fluid are also things that are produced by the means of thelia cells which include things such as glycoproteins tgf-beta and nitric oxide now let's look at some clinical anatomy of the lung Laura beginning with pleuritis which is inflammation of the parietal pleura mainly due to viral infections clinical signs include shortness of breath and pleuritic chest pain which is characterized by essentially pain when breathing in and also pleuritis has a characteristic pleuritic rub which can be heard during expiration and inspiration sounds like creaking or grating sounds something like this again the main cause are viruses but autoimmune conditions can also cause pleuritis the next clinical Anatomy condition for the lung pleura is plural effusion which is accumulation of fluid in the pleural space usually as a result of inflammation of the pleura standing up means gravity will push the fluid down the area where the fluid is means that there is decrease in breath sounds if you try to listen to it there and also there will be dullness on percussion because it's just solid all fluids there will be also decrease in lung expansion here's an example of a chest x-ray with someone who has left-sided pleural effusion here is the meniscus sign and as you can see all this colored here is fluid within the pleural cavity usually small pleural effusions resolves alone but if there's so much and if you want to diagnose the cause of the pleural effusion you can do what's called a cardio Santi SACEUR pleural tap the procedure is essentially where your aspirate excess pleural fluid and this is both therapeutic but also the fluid can be analysed to see what is in it this can help the doctor help them identify a potential cause of the pleural effusion either heart failure or cancer or autoimmune for example the next clinical anatomy condition is a pneumothorax which is essentially where you have accumulation of air in the pleural space pneumo as an air thorax is in the thorax now there's two main mechanisms of how people get pneumothorax these are spontaneous pneumothorax and open pneumothorax spontaneous pneumothorax is usually a result of a ruptured bulla seen in lung conditions such as COPD this rupture of bulla causes air essentially to leak into the pleural space and so when there's so much air that occupies a space it will actually push against the lungs causing partial collapsing of the lung and open pneumothorax is usually due to an external trauma which causes air to leak into the pleural cavity from the outside and this also causes the lung to collapse again when you perk us it will actually be hyperresonant because there is air within that cavity this means that when you auscultate the area there will be all usually reduced breath sounds or even no breath sounds as you can see here is an example of a chest x-ray of someone who has a left-sided pneumothorax as you can see this line denotes the lung and it's being pressed by air that's entering the pleural space there's something called pneumothorax and then there's something called tension pneumothorax which is a life-threatening condition it is really where there's over accumulation of air in the pleural space usually as a result of a valve mechanism so it's usually from an external trauma causing an opening such as maybe like a cot or a wound now the opening somehow works as a valve in which when you breathe in Inspire air will come in and it will increase the pleural pressure and when you expire during expiration however the air can't leave the pleural space because the hole closes up like a valve and so you can imagine with each inspiration pressure will build up in the pool pleural cavity this causes the lungs to collapse even more and also the large increase in pressure will stop pushing other structures around for example it will cause tracheal deviation to the opposite side of where the tension pneumothorax is it will also push against the heart causing decreased cardiac output and hence hypotension the compression of the heart can also mean there is an obstruction of the hot filling system causing a characteristic raised in jvp here is an example of a chest x-ray of someone who has a left-sided tension pneumothorax as you can see all this area here is air not within the lungs but within the pleural space and it is collapsing it's totally collapse the lung and also starts to push against the other structure pushing all structures to the right you can see tracheal deviation you can see compression of the heart this is a life threatening and because tension pneumothorax is a life-threatening condition what needs to be done is an emergency needle decompression classic approach is second intercostal space midclavicular with a needle allowing air to essentially exit from the pleural space


  1. Man, just incredible vídeo! Few vídeos talk about pleura and thoraxic conditions. Thank you! Very well explained and great drawings! Subscribed!

  2. Thank you so much for your videos, I love your Clinical Anatomy videos! A really big plus for the sound of "Pleural rub", it is really hard sometimes to imagine the sound of every disease, like different heart sounds, lungs, crepitus etc. So again, THANK YOU!

  3. you don’t have a video of the ventricles and the cerebral aqueduct and ependymal cells do you? I’ve been looking and I can’t find one from you. If you don’t then i think you should make one because your drawings are amazing!

  4. I wish my doctors were this informative when I presented with pleural effusion.
    But instead all I got was two doctors in a room pointing to my X-ray ‘see that white stuff on your right lung? You have fluid there.’
    Me; ‘is it urgent?’
    Doctor1; ‘we should get it removed’
    Doctor2; ‘we can give you antibiotics and see how you go’
    Me; ‘I’m already dying from cancer and heart failure. Give me the antibiotics and discharge me doc. We’re done here thanks.’

    Not interested in anymore torture thanks. No one is ever poking anything into my body until I’m dead.
    Unless it’s a euthanasia kit. Jab away doc, jab away…

    Please call your local representative and inform them of your support for a euthanasia bill in your state. We need to allow our loved ones the CHOICE to die with dignity instead of FORCING them to rot slowly in agony.


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