in order to understand the origin of abdominal pain and in order to understand the difference nervous pathways involved in pain conduction, we will take a look at your automatic nervous system. As you can see in view here, we now can also see the thorax up here. We will take a look at the thorax as well, because that's the autonomic nervous system actually goes down from the skull and the head, which is located more up here, down towards the different organs. Here in the middle, we can actually see the diaphragm and just up from the diaphragm here in the middle, we can see the heart. The heart is still located in its pericardial sac which is protected by visceral fatty tissue. That's the yellow tissue we can see here. The organ we can see here is the left lung. The left lung is still in place. The right lung which was originally placed here. So this is the right pleural cavity. But it has been opened, in order to view the autonomic nerve system. First we'll start with the sympathetic nervous system. The sympathetic nervous system is mostly made up by the two sympathetic trunks. The sympathetic trunks are large bunches of nervous tissue, which actually run from the base of the skull up here, all the way down to the tail bone way down here. We have two of these located one either side of the vertical column, which is located way down at the different tissues we can see here. And through the sympathetic trunk, all the sympathetic enervation reaches the various visceral organs. So first off, we'll take a look at the sympathetic trunk here. That's in the right pleural cavity. In order to do this, we must actually open the mediastinal pleura covering the pleural cavity here. It's already opened. So now I just have to move the pleura around down a bit, like this. So, what I'm lifting now is the mediastinal pleura And now we've got a clear look at the compartment deep through the pleura. We can see some yellow fatty tissue. If we take a close look, we see a bluish white line. And this actually the right sympathetic trunk. So the sympathetic trunk, runs from the base of the skull more superiorly, all the way to the tail bone, or inferiorally. And the sympathetic trunk only communicates with the spinal cords on the thoracic and lumbar levels. This communication is done through these very small branches. We can see one clearly here. These branches are called ramus communicans. Through such ramus communicans the communication is made with the spinal cord and the central nervous system. Enervation reaches the sympathetic trunk through these different branches. We can see some more here and here. And from the sympathetic trunk, the enervation reaches the organs. And this connection is done through splanchnic nerves. Right here, we can see a large splanchnic nerve emerge, so this is a thoracic splanchnic nerve. Another little branch here, this actually forms the great splanchnic nerve. The great splanchnic nerve actually bounces through the diaphragm, we can see here, then reaches the abdomen and then will locate itself around the celiac trunk to invade most of the foregut. So this is sympathetic nervous system in the thorax. We also have the parasympathetic nervous system and most of this is done through the vagus nerve. For the vagus nerve, of which we also have two, a left and right one is located a bit more up here. So again here, we have the heart in it's pericardial sack. You see a blood vessel here. It's actually an artery the common carotid artery, which feeds blood to the neck and the head. Blood is venously returned through this vein you can see here. This vein is an intrajugular vein, and when we look between these veins. Have to remove the vein a bit. Now, we get a clear look on this nerve here. This is the vagus nerve. So the vagus nerve supplies most of the parasympathetic enervation, actually for most of the entire body. These two vagus nerve actually travel more down into the mediastinum. And they locate themselves around the esophagus, which actually they'll go behind the heart here. And the vagus nerve actually form a plexus around, so a network, around the esophagus, located here. Then they emerge again in the abdomen.