 So this is going to be a demonstration of the thoracic wall anterior thoracic wall which we have removed from this cadaver here So first let's quickly identify the parts of the skeleton here. This is the Maribriam sternum. This is the body of the sternum This is the Zephoid process So therefore, this is the Maribriam sternum joint or the sternum angle of Louie. This is the Zephoid sternum joint These are the ribs This is the first rib on either side second third fourth and so on and so forth and the last rib is the Seventh rib. So therefore the ribs form what is known as the sternum costum joint The lateral portion of the rib is bony. The medial portion of the rib is cartilaginous So therefore, this is a costocondral articulation. After the seventh rib, the eighth ninth and the tenth ribs They articulate directly with the seventh ribs in what is known as the intercondral or the chondrochondral articulation Let's take a quick look at the Maribriam sternum. This is the jugular notch of the Maribriam sternum This is in the root of the neck These two are the articulation for the medial end of the clavicle This is articulation with the first rib and we can see the first rib has got several other structures attached to it Namely the subclavius muscle and the scalyness anterior muscle Incidentally, this side first rib has got an exostosis and we can feel exostosis on the inner surface also The first rib forms a synchondrosis with the Maribriam sternum There is no movement at this joint with the first rib This is the second rib and we have mentioned that the secondary particulates with the sternum angle of louis How do we count the intercostal spaces the intercostal spaces are below the corresponding rib? So therefore, if this is the first rib, this is the first space second rib This is the second space and so on and so forth This is the costal margin And this is the z-fight process this angle that we see here This is referred to as the subcostal angle This is referred to as the Maribriam sternum angle or the sternum angle of louis So these are some important landmarks that we can see from the first To the seventh ribs. These are known as two ribs Eight ninth and tenth ribs which articulate with the seventh rib They are known as false ribs because they don't articulate with the sternum And the 11th and 12th ribs which you cannot see are called floating ribs because they articulate only with the vertical column They don't have any anterior articulation. So this is the classification of the ribs Now let's focus on the muscles that we see here These are the intercostal muscles The intercostal muscles are in three layers Outermost is the external intercostal muscle And if you take a close look you'll see that the direction of fibers are as if the hands and the pocket That means they're going downwards obliquely and inferiorly Then we have the next layer of muscle and for that I'm going to remove a few fibers of the external Show the next layer of fibers and we can see some of the fibers of the next layer This is the internal The internal direction of fibers are exactly Opposite to the external as if the hands are crossed over to the opposite chest Internal is for two parts One portion which is in relation to the bony portion of the ribs that is known as the intercostious part And there's another portion which is in relation to the cartilaginous part of the ribs Which is where my instrument has gone in that is known as the intercontral part So that brings me to the action of the external intercostal and the internal intercostal The external intercostal is responsible for elevation of the ribs during forced respiration The internal intercostal the interosseous part is responsible for depression of the ribs during forced respiration While the intercontral part is responsible for again elevation of the ribs during forced respiration The principle behind this is that when the direction of fibers are at right angles to the direction of the long axis of the rib then it produces depression and when the direction of fibers are almost parallel to the direction of the long axis of the rib like in the intercontral part then they are responsible for elevation of the ribs. The external intercostal if you continue further medially as we can see them here medially the external intercostal disappears and it is replaced by this membrane here we can see the membrane of this space we can see the membrane in this space I have lifted it up with my instrument and we can see the membrane in this space also. So, the medial portion of the external intercostal is replaced by the external intercostal membrane closer to the sternum the internal intercostal also does the same thing on the posterior aspect which we cannot see here as it goes posterior towards the vertical column it disappears and it is replaced by the internal intercostal membrane and deep to the internal intercostal we have a very thin muscle layer which is known as the innermost intercostal subcostal and transversal thoracis I shall show part of it when I turn the chest wall. Let me tell you quickly now movement of the ribs in respiration the upper ribs up to the seventh ribs they are responsible for what is known as pump handle movement of the chest wall where by virtue of their movement they increase the anterior posterior diameter of the chest the lower ribs the eighth ninth and tenth ribs they are responsible for what is known as bucket handle movement of the chest whereby they increase the transverse diameter of the chest wall and of course not visible here is the diaphragm which when it moves down and up it changes the vertical diameter of the chest wall before I turn this chest wall here I would like to show you this neurovascular structure here which I have lifted up this is one neurovascular structure you can see it is running in relation to the lower border of the rib above and this is another neurovascular structure which is also running in relation to the lower border of the rib above whenever we need to do any intratheuristic procedure like for example pleuro synthesis we should insert the needle closer to the upper border of the rib below and further away from the lower border of the rib above the reason being the neurovascular structures are running close to the lower border of the rib above so therefore in pleuro synthesis we usually use the fifth intercostal space in the mid axillary line for the pleural tap in case of pleural effusion likewise if we want to anesthetize an intercostal space we must remember that the main neurovascular bundle the vein artery nerve runs in relation to the lower border of the rib above and the collateral branch runs in relation to the upper border of the rib below therefore we have to anesthetize two sets of neurovascular bundles to completely anesthetize one intercostal space so these are some of the search paper procedures and clinical applications of the chest wall thank you very much for watching Dr. Sanjay Sanyal signing out if you have any questions or comments please put them in the comment section below have a nice day