 This is the second part of the dissection of the dermatothoracic diaphragm. We have some important clinical correlation pertaining to the esophageal hiatus. We can have what is known as the hiatus hernia where a portion of the stomach which has been removed here can push into the thorax through the esophageal hiatus and that is known as hiatus hernia. We can have two types of hiatus hernia. One is the sliding hiatus hernia when the esophageal gastric junction itself gets pushed up and there is loss of sphincter mechanism which results in reflux esophageitis and there is another type of hiatus hernia which is known as parisophageal hiatus hernia where a portion of the fundus of the stomach gets pushed in and that does not produce so much of reflux esophageitis and of course we can have mixed hiatus hernia. That is one thing we can get in the esophageal hiatus. Now let's take a look at some other minor openings in the diaphragm. Let's start off from the anterior aspect. This is the sternum and attached to the sternum are a few slips of muscle fibres in the midline which are the sternal fibres of the diaphragm and thereafter the rest of the muscle fibres as I mentioned earlier these are all the costal muscles, the costal. So therefore there is a small opening between the sternal fibres and the costal fibres and that gap is referred to as the antrilateral gap or the sternocastal gap of lary and passing through the sternocostal gap of lary are these vascular structures which I have lifted up on the left side. This is the superior epigastric artery and vein and we can see they are coming from here and they are running on the posterior aspect of the rectus abdominis muscle on the left side. Coming to the right side this is the rectus abdominis muscle on the right side and here also we can see these are the superior vessels the artery and the vein which are coming onto the posterior aspect of the right rectus. This superior epigastric artery is one of the terminal branches of the internal thoracic artery at the level of the seventh rib it divides into a superior epigastric and musculophrenic. The musculophrenic runs on the laterally and it supplies the diaphragm. The superior epigastric runs on the posterior aspect of the rectus abdominis muscle on both the sides. So the superior epigastric artery on both the sides we can see clearly are emerging through the sternocostal gap or the sternocostal triangle or the antrilateral gap of lary. We can see it on the right side here and we can see it on the left side here. Rarely this can be a site of hernia and that is known as the hiatus of the hernia of Morgagni. It is not very common but it can occur through the antrilateral or the sternocostal gap of lary. Now let's take a look at another important area of the diaphragm. For that we will have to look on the posterior aspect. I am looking on the left side. If you look very carefully you will see that these are the muscle fibres coming from the lumbar vertebrae and the fibres are going up like this and getting inserted into the central tendon. And if you look further laterally you will find these are the costal muscles which are coming from the ribs and they are getting inserted into the central tendon. In between the lumbar portion and the costal portion we can see a triangular area here and if I stretch it like this we can see it much more clearly. This is referred to as the lumbo-costal trigone or the lumbo-costal triangle. This portion is unique and you can see it clearly here in so far that this does not have any muscle fibres. Here only the endothoracic fascia on the abdominal side and the endothoracic fascia on the thoracic side they are fused together without any intervening muscle and this is a potential area of weakness. When there is a blunt injury to the abdomen this portion can rupture on the left side and it can produce what is known as a traumatic diaphragmatic hernia. In newborns this can be a site of herniation which is referred to as the congenital diaphragmatic hernia which is most often on the left side and that is also referred to as hernia of boctalic and this is known as the hiatus of boctalic. In newborns this results from failure of closure of the pleuroperitoneal membrane to close the pericardioperitoneal canals on the left side. Hiatus of boctalic producing a hernia of boctalic on the left side is much more common than on the right side. It is the ratio is approximately 95% on the left side to 5% on the right side. Let's take a look at the same triangle on the left side. Again if you look very closely you find that these are the costal fibres muscles and these are the lumbar muscles between there is a small triangular area which is bereft of muscle fibres. So this is the potential site of weakness but herniation on the right side either congenital or traumatic is as I said very uncommon because the liver is located here but we can see the lumbocoster triangle on the right side also. So that is about the lumbocoster triangle or the lumbocoster triangle. This is an x-ray of a newborn who was still born with congenital diaphragmatic hernia of boctalic on the left side. I have only mentioned about the maternal supply of the diaphragm and that is the phrenic nerve C345. The phrenic nerve is also sensory to the central portion of the diaphragm and that is the reason why if there is a diaphragmatic irritation in the dome of the diaphragm then it can produce referred pain to the respective shoulders. The referred pain being because the root value of phrenic nerve is C345 and the referred pain to the shoulder is via the supraclavicular nerves whose root value is also C34. So if there is irritation for example collection of blood from the spleenic rupture under the left dome of the diaphragm or any collection under the right dome then it can produce referred pain to the respective shoulders. That brings me to the peripheral portion of the diaphragm. The sensory supply to the peripheral portions of the diaphragm is by the lower six intercostal nerves. That is 7th, 8th, 9th, 10th, 11th, 12th. That is about the nerve supply. Having mentioned the major orifices and the minor orifices there are a few other insignificant openings in the diaphragm which give passage to various structures. For example on the left side we have the hemiasigus vein which enters the thorax from the left side through unnamed orifices. Similarly the left phrenic nerve also comes by itself unnamed orifices from the left side. So these are some other and I have already mentioned the greater, lesser and least spleenic nerves which start from the thorax and they come to the abdomen. This is why they are also referred to as the thoracoabdominal spleenic nerves. They enter the abdomen through the crura of the diaphragm namely the right crust and the left crust and those openings are unnamed openings through which they pierce through and enter the abdomen. So that is all about the diaphragm and its orifices and its respective clinical correlations. Thank you very much for watching. If you have any questions or comments please put them in the comment section below. Have a nice day.