 So this is the demonstration of the posterior chest wall. This is the prone cadaver So this is the left side of the chest wall and we are demonstrating this from the left side of the cadaver. In order to demonstrate the chest wall posteriorly, we have to reflect the following structures. First, we reflected this muscle here. This is the erythrospinate. Part of the erythrospinate, which is known as the Iliocostalis. This is the posterior layer of the thoracolumbar fascia that we have reflected. And this is the other part of the Iliocostalis. The next muscle that we have reflected is this one. This is the longasmus. So now we have reflected the longasmus also. And the third muscle that we had to reflect was this one. This is the spinalis. So we reflected these three muscles of the erythrospinate and this is the remnant of the latsomus dorsi. Which also we have reflected. Superiorly, we had to retract the scapula with its attached muscles and we can see the remnant of the latsomus dorsi here also. Immediately, we reflected the trapezius muscle and we can see the trapezius muscle here. Having reflected these muscles, we see the space here. These are the transversal spinalis muscles, which are located deep to the erythrospinate muscles. And this muscle that we see in front of us, this is the semi-spinalis and deep to that will be the multifidus and the rotators. These transversal spinalis muscles, as the term implies, they are located between the spinalis process, which is here and the transversal process of the vertebrae, which are here. That's why they are called transversal spinalis muscles. They are the deep, intrinsic, minor group of muscles at the back. Extending from the transversal process to the rib, we have these ligaments. These are known as the lateral costotransversal ligament. This is one lateral costotransversal ligament here. This is another lateral costotransversal ligament. Let me first mention accessory muscles of respiration that we can see here. We can see this muscle here, with the shiny, aponeurotic expansion fibers here. This is the serratus posterior superior. And we can see that the fibers as they go down, laterally they become more flesh. Then we have another set of fibers, which are very similar in appearance. We can see that these fibers are very shiny, aponeurotic, and further, actually, they are more fleshy. This is the serratus posterior inferior. The serratus posterior superior is responsible for elevation of the ribs, and the serratus posterior inferior is responsible for depression of the ribs. Both of them have proprioceptive function. The serratus posterior inferior was located under the latsomus dorsi muscle, which we can see here. The serratus posterior superior is located under the rhomboids and the libators. And we can see the revenant of the rhomboids major here, and the rhomboids minor higher up. Now let me point out another accessory muscle of respiration that we can see here. If we look closely, we can see these muscle fibers coming down from the transverse process above to the rib below. Next, from the transverse process above to the rib below. From the transverse process above to the rib below. These are the libatoris costorum. They go obliquely down, and therefore we have already guessed it. Their action is to elevate the ribs. Now if you look very closely, we can see a small triangular space. Bounded by the libatoris costorum, the inter-transverse ligament and the lateral costotransverse ligament. In between this triangular space, we have a neurovascular structure coming out. And that is the torso ramai of the spinal nerve which supplies the muscles of the back. And we can see we have picked up one of those. And we can pick up another one here also. These are the torso ramai of the spinal nerves which come out through this triangular space. Bounded by the libatoris costorum, the inter-transverse ligament and the lateral costotransverse ligament. 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.