Cardiac and Cranial Membranes

So at this point it's time to insize the peritoneum itself and I'm just going to do so right down the midline. Seems like as good a place as any. I'll do it in the upward direction as well. As a textural layer the serous membranes represent a significant shift from the fibrous outer layer of fascia to which they adhere. The peritoneum demonstrated here in the cadaver form while missing some of the liquidy translucence of the living tissue nonetheless conveys its distinct quality as a connective tissue layer with a mesothelial intercoding which renders its contact with the abdominal contents slick, fluid and filled with the motions of life. The excitement of encountering the abdominal viscera themselves tends to pull the student too quickly past a thoughtful encounter with the parietal peritoneum. Whether acknowledged or not its influence is undiminished and much of what is accomplished in visceral work may derive in part from the stimulation and energetic reawakening of this amazing tissue. Each textural layer of our body might be considered to have a particular vibrational tone or frequency which like the characteristic emission and absorption spectra which identify each atomic element express and receive very specific types of information. As surely as the eyes, ears and nose are tuned to particular frequencies for our general interpretation of our experience, so too do the superficial fascia, deep fascia and membranous layers in virtue of their distinctive structural composition serve as matrices of vibrational interpretation. It's up to the intrepid somana to determine through study exactly what are the particular tonal qualities and vibrational endowments inherent in a healthy expression of each of these different tissues. The peritoneum is tying into the liver, you see that? Because the peritoneum is the wall layer, the parietal peritoneum doubles back here and becomes the visceral layer over the liver. And on the same way on the other side, the wall layer comes across here and dives down and becomes the skin of the liver, and in between we call that the falciform ligament of the liver. See where the roof of the peritoneum on either side dives down, right? The parietal peritoneum dives down and creates a septum and a skin over the liver. So that's the falciform ligament of the liver, and this is the round ligament of the liver. When we're inside of the abdomen, ligaments aren't tough fibrous cords tying bone to bone, we're inside of the abdomen, ligaments are peritoneal relationships of one organ to the next, or of one organ to another aspect of the peritoneum. So the gastro-splenic ligament is peritoneum spanning between the stomach and the spleen. And here the falciform ligament is the wall layer of the peritoneum diving down to become the skin layer of the peritoneum, the visceral layer over the liver, the skin of the liver here. I save for the next volume of this series a thorough exploration of the viscera and their many particular peritoneal relationships. For now, I'll just briefly address the surface projections of the organs themselves. I just want to take a gander at the layer of the land, just as it is in place, right? We see the intestines right here now. It's often the case that there's one more layer that you encounter when you open up this bag. It's called the greater omentum. It's a great yellow apron that drapes over the intestines here. Now I don't see the greater omentum straight off, although I do see some yellow fuzzy stuff up here. Now the greater omentum has a motile properties. The greater omentum can move. It's a traveling organ. It's comprised of four layers of this type of peritoneal sheeting, four layers of it. It's embedded with fat and then it's receiving its four layers, two from the stomach and two from the transverse colon, right? The skin of the stomach and the skin of the transverse colon front and back, either one, contributes the four layers to the greater omentum and then the greater omentum hangs off of those organs and drapes over here like a blankie, but I don't see it. Maybe it's snuggling somewhere. Okay, maybe it's snuggling somewhere. That's my first suspicion. You see, because when a person is sick, the greater omentum snuggles it like a blanket. The greater omentum can flip up and cover the liver. The greater omentum can gather around a sick stomach or draw itself against the peritoneum if it's peritonitis or there's been a surgical injury, scar, opening wound and then it's closed up and there's a wound there and the greater omentum will cling to that wound and protect it. It's quite amazing that way. It's like your own internal snuggle blanket and over here I see the kind of tissue that normally represents to me the greater omentum. The man is very trim. It's often not uncommon to see a lot of fatty tissue inside of the abdomen. We don't see that with Mr. Agape as we noticed in his superficial fascia was extremely thin too, but I look at this yellow tissue here. I see the transverse colon in the stomach here and I'm wondering if either was his greater omentum cut or is it snuggling? It could be cut if there's a surgery. While I'm not able to determine the exact surgical history of this form, I can guess that his greater omentum may have been partly reduced during the removal of his appendix though it is simultaneously atrophied due to the particular constitution of this individual as a comparison we can observe the greater omentum and transverse mesocolon of the female form which we have been studying in the earlier volumes. Her omentum is a typical presentation of someone with a more endomorphic morphology. So where was that? It was tucked in here right?

This greater omentum now it's still laying in place. I haven't disturbed it. Wanting to appreciate what I see first. Rather what my hands can tumble through because it's a complicated space. My hands start tumbling and displacing everything but it's helpful to understand a form by just seeing what do we see when we come in. You see this broad bag here. It's very broad and that's the beginning of the large intestine. These tubes appear smaller right? They look like the gyri of the brain. The swirling back and forth curves of the brain with the sulces in between them and the intestines are not much different than that. Here we see this broad tissue continuing. You can see a little bit of air. It's a hollow organ. Here we see this intensely green little bag here. That's the tail of our gallbladder. So we're looking at surface projections. Here we see our liver right? Left lobe of the liver and then we see a more pale tissue here. It's collapsed on itself. What if I lift it up? It's a tough meaty. It's like a leather bag this thing. It's the stomach. It's not the whole stomach. This is just the surface projection of the stomach. So we're looking and we're standing in front of the mirror and we're seeing organs. It doesn't mean that the whole stomach is huge. It's going clear to the back. It's a surface projection. The esophagus runs along the spine so the stomach runs deep but in front it presents this little bubble. We saw our omentum here. We see this great green band coming across the front here. It's a transverse colon. All through here we see small intestines, small intestines. Down here, coming around the bend of the ASIS, the anterior superior iliac spine on the left side. On the right side we have the cecum. On the left side we have the sigmoid colon. It's taking an S curve around the bend here, down into the rectum. More small intestine, more small intestine. All these loops of the small intestine that you were handling when you were lifting the bag. That was intestines in your hand. For the sake of completeness in our presentation of the membranous layers of the abdominal viscera, we can briefly peek ahead to encounter the visceral peritoneum of the stomach as I explored in the eviscerated organs on the fourth volume of this series. If I peel the, see I'm peeling the visceral peritoneum off of the stomach. I'm peeling the skin of the stomach. And you can see this incredible strong muscle fiber here. The peritoneal coating of the stomach when removed, like the pleura earlier, recoils and nearly vanishes when disrupted from its relations to what lay beneath it. Reviewing the fibrous and serous layers of the abdominal fascia, we've carefully studied the transverse alice fascia, the parietal peritoneum, and finally the visceral peritoneum. So, there's often loose aerial or fascia around the fibrous pericardium. And that's what we're looking at here. Just loose aerial or fascia around the heart. And it's possible to sort of tease that away. And I'm not entering the fibrous pericardium when I do so. In fact, I can rub this stuff off with my hands. Oftentimes there's quite a bit of fatty deposition around the heart. It's very common. The fatty deposition is covered by pleura here, the mediastinal pleura. This is stuff in the middle. So, it's covered by the mediastinal pleura. So, even though we're seeing this shape coming out here as I scratch away this fatty tissue, and we see these little beautiful blood vessels here, those are the blood vessels of the fibrous pericardium as opposed to the blood vessels of the heart itself. The blood vessels of the heart itself are larger. So, I'm just scratching away here with my fingertips. And I'm rubbing back this loose aerial or fascia. I'm going to keep on rubbing away this loose aerial or tissue here to get a sense of where I am. When I do so, now I'm on the other side. And again, I'm rubbing, I'm peeling up. Basically, I'm peeling up. As I rub away this fat, I'm peeling up the mediastinal pleura on the far side of the body here, from where you all are viewing. And I pull, it's covering the fibrous pericardium. So, the sac of the heart, the fibrous sac of the heart, right, just has this loose fatty tissue over it. Here's the fibrous sac of the heart. The heart is very large. In this instance, he has what I would call an enlarged heart. Okay, because here's our sternum here. And pretty much anything that you get past this edge of the sternum, anything on this side is an indication of enlargement of the heart. The heart in terms of more normal presentation, the heart pretty much peters out at the lateral right side border of the body of the sternum. But in his case, he's got another inch of heart over here. So, I'm just acknowledging the fact that there's a little bit of an enlargement here. And I'm expecting to find other kinds of heart pathology out here because I saw the open heart surgery. So, I know for a fact that people have been here before and that they've done some serious work. So, I'm just peeling away this loose fascia. Oh, you know something? Forget about this one. I tried to tell you that was the thymus. That's part of it. There's more of it here. I've just come into some thymic tissue right around here. So, I have more glandular tissue that I missed when I looked at it before. Well, that's exciting. So, right along here I'm finding more glandular tissue of the thymus. That's neat. I've got a whole block of it here. It's vascular. So, all this is thymus here. And I'm sort of severing it from its blood supply. So, I'm going to tell you that. We have more thymus. All this thymic tissue.

The thymus is the place where the T cells mature. So, T cells are immune cells in your blood system and the T cells are how you recognize yourself. So, I've heard it said that the thymus is the place where you learn to recognize yourself. In a sense, it's a place of self-identity for the child. It's a place where cells learn to recognize the difference between who I am, my body, and the community of cells that represent my body and those things that are outside of my body, which would be rejected and scavenged and scoured out of the blood. So, it's part of the immune system, the thymus. I can't resist commenting that finding actual glandular thymic tissue in an elderly form that can be recognized at the gross level is rare in my experience. This was only the second time in over 100 cadavers. The thymus is at its largest size by proportion in the newborn and at its largest by weight at about five years old, after which it atrophies and generally appears as a fatty pad of tissue in the elderly cadaver form. See, we sweep from the mediastinopleura to the visceropleura. That balloon that wraps around the whole thorax, the parietal pleura, is not unrelated to the visceropleura. It's related, it's just a transition point here. So, it's all the same tissue. It's just wrapping it in different ways. So, if I sweep away, I sweep away this pleura here, all I'm doing is basically ripping it off. At this point, I'm even lifting it off of the lung. It's coming off as the skin of the lung here, see? I can just brush my finger through here and I'm actually peeling the skin of the lung back. Now, when I do so, and I pull away the pleura like I am here, what I've actually done is gone and exposed the phrenic nerve, which I can see. The phrenic nerve is here. It's running along the mediastinum and if I grab my hemostat here, I can actually just lift it up. I can scratch along that line and before you know it, I'll have my phrenic nerve. That's the nerve that's going to the diaphragm and it just runs along the mediastinum there, deep to the pleura. So, the pleura covers it and it runs along the stuff in the middle. It's one of those stuff in the middle features. When I'm scratching and scratching, I can see somehow I cut it up above, but I still have it coming down here. I must have cut it up above when I was opening the chest wall there. That's alright. I can follow it on down just like I did on this side. I have my phrenic nerve on my right side and over here, intact still, I have the phrenic nerve on the left side as it enters into the diaphragm. So, it's running along the mediastinum on both sides and it's innervating the diaphragm. So, good. We've seen our phrenic nerves, our thiamic tissue. We've gotten a sense of the parietal and the visceral pleura. Mediastinum just means that which stands in the middle. So, many times you have, if you hear some, I've heard people argue about it. Oh, the mediastinum and they think it's a particular tissue. Like, oh, that's the mediastinum. Well, like this, that's the mediastinum. That's not the mediastinum, although it's in the middle. It is stuffed in the middle, but it's not the mediastinum. The mediastinum is everything that's in the middle. If it's not the lungs, it's the mediastinum. So, the mediastinum includes the heart, right? The heart muscle and the aorta and all the branches coming off of it and the esophagus and the main bronchi and the thoracic duct and anything that's lying in between the pleura on either side is the stuff in the middle, the mediastinum. So, there are a whole number of what we would call mediastinal structures and learning about them is part of the thrill of thoracic anatomy. And so, we have a fibrous pericardium. Pericardium means around the heart. So, we have a fibrous bag around the heart. The heart itself has its skin, right? So, that's the visceral pericardium and then adhered to the back of the fibrous pericardium just like the pleura was adhered to the end of thoracic fashion, right? The parietal layer was adhered to the fibrous layer in the pericardium also. This parietal layer, the wall layer of the pericardium is adhered on the inside to this fibrous outer cover. Now, I read about these three bags in books and I didn't get it at all. I'd scratch around here and I'd make a hole and I think I had scratched off the fatty tissue or something and then I'd have the heart here and I wouldn't see a bag around it and I wouldn't see a skin on the heart that I could understand and I was like, well, I don't know what they're talking about. But then I slowly came to realize that the fibrous pericardium here, which has already been gone into by the surgeons and there's staples all over it. Staples, staples, staples, staples. It's stapled to back up together. Okay, so if I can penetrate the fibrous pericardium, see it? It's a bag. It has a sound to it. It sounds like a tough fascia actually. So if I just lift it and cut it, I'm opening the fibrous pericardium to come to this precious heart space. So I get inside of here and I'm feeling also now adhesions, okay, because there are adhesions of the fibrous pericardium to the heart in this example. So I'll go up and down. I'll open this space with my scalpel. I'll scratch along these adhesions. This is not a sliding surface I'm encountering. The visceral pericardium is adhered to the parietal pericardium so that I have to peel it away. So that's not the normal manner because this is going to limit the movement of the heart within its sac. And we'll ultimately have repercussions.

So I'm also encountering these many staples here. So there's a bunch of staples. They're stapling the layers together somehow here. So this scarring and stapling. And then if I come here, I can continue to push this adhered tissue away and try to open this heart space. I'm pulling. See these adhesions? See that little staple? A couple staples there. So we're having these adhesions then of the... Now realize this, you know, these are the upshots of heart surgery. There are 400,000 open heart surgeries a year in the United States alone. So heart surgery is a common thing. As I pull away here, these adhesions now, in the back it's easier. You see? I can slip in there easier. This is a sliding surface down deep below. But on these other portions I'm having adhesions, very many adhesions of the fibrous... So I'm pulling now. See I'm pulling down the fibrous pericardium and I'm revealing the visceral pericardium, the skin of the heart. So if I flip the fibrous pericardium over, then I'm looking here at the serous membrane, the serous layer. So can you see the difference? Actually there's a line here where I've cut it. Okay, so this shiny sheen here, that's the parietal pericardium. It is adhered to the fibrous pericardium. So I saw from the outside the fibrous pericardium and I opened it up and I see already this. Now I didn't cut that. Someone else cut that. See? So that's actually a line from where the parietal pericardium was cut in the surgery and then was put back together here. So we have a little missing patch even. And then of course we are having scar tissue here. So this is what happens. We've saved a life perhaps and gained some years but we've lost some movement which ultimately has its ramifications that we can discuss. So now I'm pushing back two layers, the fibrous layer and the parietal layer in order to expose the visceral layer here. So you can see my fingers sliding along here. What I'm doing is I'm breaking down the adhesions of the visceral pericardium on the inner surface of this fabric to the, I'm sorry, the parietal pericardium on the inner surface of this fabric to the visceral pericardium which is the skin of the heart. So I'm going to cut across here, cutting across the fibrous pericardium at this point so I can continue to open the bag of the heart space and reveal what is within it. I have to always acknowledge whenever I come across challenging surgical work, you know, I feel like I'm going where someone has gone before except they were doing it while the person was alive. So it's a tremendous skill that's involved. Now I'm sliding, again, freeing the heart from its sac here and pushing and pushing. There's an adhesion there. And I'm basically pulling away the parietal pericardium from the visceral pericardium and exposing this massive heart. And the fibrous pericardial sac extends up here over the aorta as well. And I can cut this here.

Having differentiated the fibrous pericardial sac and its external relations as best as I can, there comes a point here where we can identify the particular continuity of the tendinous portion of the diaphragm with the fibrous pericardium. The heart moves with the diaphragm and vice versa. We had anticipated this continuity earlier with our model. The shiny surface of the parietal pericardium, freed of its adhesions now, presents the normal sliding surface which we had hoped for in the healthy relation of that layer with the surface of the heart, the visceral pericardium. The heart space is a dance space and we should facilitate and support the freedom of our heart's dynamic and versatile movements whenever possible. The heart musculature wrapped in its visceral pericardium occupies the center of this image as well as a vital center of our living blood's journey through our body. The continuity of the heart itself with its prolongations in the form of the great vessels branching throughout our body is complete. The whole heart, as I prefer to envision it, has arms and legs and head and viscera. It extends itself perfectly through the entire form and there is no particular place where one can say the heart is not present. From a conventional anatomical perspective, of course, we could pass our scalpel through the great vessels and essentially amputate the heart, but as an exercise in the study of integral anatomy, I choose to emphasize its continuities. Now, the visceral pericardium, the skin of the heart, is very thin like the other visceral layers we've encountered so far by slowly scratching it away a little at a time, along with the loose, aerial or fatty tissue that smooths the contours of the organ. The process of dissection eventually reveals the actual cardiac muscle fibers and vasculature, as well as in this case the additional bypass of vessels. We'll save a detailed tour of the many beautiful structures which emerge here for another volume in the series. Suffice it to say for now that the heart is a center of life and movement and deep feeling and I am honored and humbled by the opportunity to experience and learn from the heart of another. The time has come to explore the fibrous and membranous layers that cover the nerve tree of our body, the central nervous system, the brain and spinal cord. We'll let this orange layer here represent the bony margin of that space, just as in the rib cage where we have a bony margin surrounding the organs of thorax and over a good portion of the abdomen as well. In the case of the central nervous system we have a bony casing, the skull here, and adherent to its inner surface is a fibrous layer called the dura mater, the tough mother. Now that fibrous layer serves as the periosteum of the inner lining of the skull and vertebral column in the same way that the endothoracic fascia creates an inner lining and a periosteum for the inner surface of the rib cage. Immediately deep to the dura and adherent to it is the arachnoid, the spider-like layer, a thin membranous layer which has as its analog and the other visceral space is the parietal layers, whether they be the parietal pleura, the parietal pericardium, the parietal peritoneum. The arachnoid serves as that wall layer or parietal layer adhering to the outermost fibrous layer in the cranial space in the vertebral column. Then just as in the case of those other visceral spaces, deep to that parietal layer, in the case of the cranium and vertebral column in the central nervous system we have a fluid layer intervening between the two inner membranous layers, the skin of the organ and that parietal layer. So in this case instead of a serous fluid we call it the cerebrospinal fluid, it's a very watery fluid with only a minor component of proteins etc. Nonetheless it reiterates the pattern that we saw in the other visceral spaces. We have this membrane here with a fluid layer, deep to it we'll let these white pockets represent the fluid layer because of the convolutions of the shape of the brain. The pia mater or the skin of the brain or the skin of the spinal cord follows all of these convolutions of the shape of the organ and in the consequent intervening space between the arachnoid and the pia we have and find circulating cerebrospinal fluid. Now this wouldn't be a completely blank space in reality only in our model there are very many little microscopic trabeculae that relate the tissues of the pia to the tissue of the arachnoid but for the sake of our model we let it look like a space where fluid can circulate. In the case of the ribcage when I dissected between the bony frame in the back I created windows through the fibrous periosteal layer the endo thoracic fascia and when I finally removed the bony basket the remainder of the fibrous inner lining was removed along with it it remained firmly adhered to the bony inner surface. The cranium is a different sort of bony covering than are the ribs because at least in the adult the skull offers no apparent soft tissue windows for peeking into the underlying tissues we have to create them. So for the cranium I've cut the bone off camera on several different cadaver models and with some effort separated the bone from its own inner lining leaving that fibrous periosteal layer the dura mater intact. We can see here that the bones are knit closely together in the skull the joints of which are very difficult to disarticulate we call these joints sutures and they very much represent a stitching together of the bones. I cut the skull in a circular way but this doesn't follow any anatomical contour except the beautiful egg shape of the skull in general. The sutures of the cranial bones fuse over time and the degree of fusion is an indicator of age. I've had craniosacral therapists in my class almost expecting the cranial bones to fall apart based on their felt perception of movement of the cranial bones of their clients. The heightened perception of a sensitive hand is capable of acting as an amplifier for motions whose actual range is very limited. The inherent active contractility of myofibroblasts in the dura mater may also transmit sensation as well as general tensions through the living bony matrix. Finally therapists can also perceive with their touch rhythmic energetic phenomena which are surely under described in conventional literature. The riverine paths which we see on the inner bony surface are the impressions of the blood vessels of the dura mater. The bony tissue is deposited and formed in the fabric of this periosteal membrane and its textural features are consequently mirrored in the skull. Different tissue qualities from one form to another enable us to highlight one aspect or another of the nature of the form. Here the vessels which pattern the dura are easy to see. In the case of the form here which I refer to as Mr. Agape, the incredible sheen of the tissue is evident while the vasculature is invisible. A particular feature of the dura mater is that it is actually a doubled layer.

The surface we see exposed here from which the bone has been removed is called the periosteal layer and its deep surface is called the meningeal layer. The periosteal layer adheres to the cranial bones and the meningeal layer adheres to the arachnoid deep to it. We don't see the arachnoid immediately though because the two dural layers come together in such a way that a number of special channels called sinuses are formed between them. The sinuses function as veins for the brain. They're lined with the very same lining as the veins elsewhere in the body. These are also an outlet for excess cerebrospinal fluid. Here I'm demonstrating the superior sagittal sinus. I can keep cutting and cutting here and this is as real as any fresh tissue sample even though our cadaver is somewhat dried out in the external tissues. We are inside the skull here protected from the air and so the tissue seems quite fresh. You can see the beautiful shine of the dura. Here we can actually see in this reddened area we have some venous blood and there's our proof that the blood is indeed draining here. I have some coagulated venous blood which I can remove. With the blood removed the inner surface of the right lateral or transverse sinus is exposed and ultimately I open the other side as well revealing the indentation between the upper portion of the brain the cerebrum and the cerebellum. The venous drainage of the dura is consistent from one form to another. Here we see the joining channels of the superior longitudinal or sagittal sinus with the lateral or transverse sinuses in a female form. The tissue pulls in at the center point and this pattern leaves an impression on the bone as well. The cranial bones are constantly conforming to the membranous stresses and tensions placed upon them whether normal or pathological. The relief of these distorting stresses through manual therapies can go a long way in relieving the chronic problems which can arise from distortions of the membranous tensions. In sizing the fibrous dura mater out of place other than the sinus pathways enables us to reflect the dura back revealing the arachnoid layer draping and containing the convoluted gyri of the brain. On a different form I've cut and folded the dura back to reveal the arachnoid layer over the cerebrum and cerebellum.

A closer look reveals the very different texture of the meningeal surface of the dura which is to say it's underside the side normally in contact with and adhered to the arachnoid. The dura's underside is quite smooth as compared to the periosteal surface. There is some debate in literature over the very existence of a potential space between the dura and the arachnoid referred to commonly as the subdural space. When differentiating the dura from the arachnoid at the gross level they seem to come apart quite easily when inspected at a microscopic level tears in the mesothelium of either membrane indicate their intimate connection in the living. Drawing the dura back reveals an area of normally very strong adhesion between the dura and the arachnoid at the center line. Commonly one encounters here small hardened granules these arachnoid granulations draw the arachnoid through the dura even creating fissures in the skull. In so doing they generate pathways for the movement of excess cerebrospinal fluid from the subarachnoid space into the superior longitudinal or sagittal sinus which we opened earlier. The arachnoid is a very thin and transparent elastic membrane underneath which fluid circulates over the pia mater the brain's surface. The arachnoid spans the numerous sulces of the brain while contacting the pia directly where it overlays the undulating gyri which give the brain its characteristic surface features. The particular convergence of the arachnoid and the dura at the center line also derives from the fact that a number of cerebral veins are draining into the sinus at this point. As I sever the relationship we're able to gain our first view of the fox cerebri that arching sickle shaped prolongation of the dura mater which creates a fibrous septum between the hemispheres of the brain. Where it meets this center line the arachnoid drapes downward on either side of the fox covering the deeper midline surfaces of the hemispheres. Removing the right hemisphere of the cerebrum we gain a full view of the internal prolongations of the dura while they remain in place. The remainder of the dura both lines the skull and covers the cerebellum with that transverse fabric known familiarly as the tent, the tentorium cerebelli. The fox cerebri is a front to back extension of the dura arching in the sagittal plane. Moving posteriorly the dural membrane sweeps into a relatively transverse plane to form the tent of fibrous fascia over the cerebellum. Tension on any part of the fabric of the dura transmit throughout the whole of it whether those tensions are generated locally through hypertonicity of the membrane from its own inherent active contractility or even if the tension is generated by torsional forces at a distance in the form. Many times I've witnessed the twists and rotations in the spine or hips of a cadaver form reiterated clearly in the cranium. An educated and healing hand can leverage those same torsions at the head or at a distance to create relief and restore balance to the whole person.

And it adheres to the skull and I have to peel very hard to get it to come away. I'm peeling with my hemostat here and it is possible to get the whole dura to peel off. It's quite the project. In this instance I chose to leave the fibrous membrane in place in all of its dramatic complexity while removing the brain. As an alternative example I demonstrate instead the brain and spinal cord removed from the cranium with the dura still intact, this time surrounding the central nervous tissues. Looking down the body with the occipital bone of the cranium removed we can observe the continuity of the dura through the foramen magnum at the base of the skull and along the vertebral column here with the bony neural arches removed. At the tail end of the spinal cord a window through the dura has been cut. The neural tube with its fibrous dural wrapping actually extends clearly all the way into the sacrum. This is dural stretching. All you have to do is bend your head forward and bend your head back to stretch your dura. There you go, nice. So all the digger in the world is never going to surpass a little bit of yoga. That's beautiful, cool. Okay, that's awesome. I'm going right down the spine. I'm following all the way down, all the way down in the end, flexion and extension, stretching the dura. And as you continue to do it, it creeps down. You can start with the cadaver and you won't get any stretch even in the cervical. Then you do it five, six, seven, ten times and all of a sudden it's stretching all the way down to lumbars. Exercise. You can now move it.

In the living, the nearly transparent arachnoid would be slightly less collapsed upon the brain tissue than it is here as the cerebrospinal fluid normally circulates beneath it. The arachnoid is a noticeably vascular membrane containing numerous large vessels. While not conforming to all of the deepest surfaces of the brain, it does drape around all aspects of the central nervous tissue generally. Even without the energies of life, the web of the arachnoid presents itself as a veil of great beauty and complexity. Along with the other membranous layers, its structure belies functions not merely mechanical but also conductive and electromagnetic which we can leverage for greater health. With the upper portion of the dura removed and the fox cerebro, no longer obscuring the view, it is possible to follow the arachnoid down between the hemispheres of the cerebro and follow it as it crosses from one side to the other over the corpus callosum, the brain tissue relating the right and left hemispheres. By cross-sectioning that white matter of the corpus callosum, I necessarily cut the arachnoid as well. It is the pia and not the arachnoid which lines the ventricles interiorly. Since the arachnoid adheres to the meningeal layer of the dura, we can trace it down the spinal column as well. At the base of the cerebellum near the foramen magnum of the skull, the arachnoid spans the hemispheres creating a larger space for a cerebro spinal fluid to circulate. Yeah, pull back here. Excellent. The sound of the dura and arachnoid being pulled apart indicates, even at the gross level, their intimate relationship, the arachnoid reflecting light here as it spans over the dorsal nerve roots and spinal cord curls up and vanishes at the touch of a scalpel. I'm going to peel away some arachnoid now, okay? Okay. It has some integrity. Then the pia is on the spinal cord. Okay. With the dura cut and the diaphanous film of the arachnoid reflected, the spinal cord presents the pia mater as its surface coat. The string-like white fibrous matter running along the spinal cord deep to the dorsal nerve roots are called the denticulate ligaments, which are fibrous prolongations of the otherwise thin and soft pia mater. These things here, these are the nerve roots. All these little babies are called the dorsal nerve roots because we're, of course, approaching this from the back. Now, the dorsal nerve roots themselves are covered in pia mater as well, so that unlike the dura and the arachnoid, which peter out where the nerves exit, the pia continues along as a surfacing layer along the extent of the nerve. The nerve roots become longer and longer as we move down the spinal cord, ultimately forming a horse-like tail in the lumbar region, the cauda equina. If you look very closely at the midline of the cauda equina, you can see a slender whitish filament amidst the brown-red nerves. This extension of the pia is known as the phelum terminale. I must admit, I find the membranes and the structures at the center of the nerve tree breathtaking. Here, with the whole brain removed, with the pia covering the cord and the arachnoid still mostly intact over the brain, we are witness to and find ourselves unwrapping a most extraordinary and extremely underestimated gift. The poorest beggar and the most honored kings and queens stand as equals with respect to the untapped powers of the deliberately intending and carefully attuned human mind with the infinite potential of the brain at its service. The power inherent in this form has, from my judgment, not yet been tapped, steadfastly awaiting our commitment to our own creative potential. Here, the three layers have been prepared in a way that each can be reviewed.

First, the double-layered and fibrous dura mater, opaque and imprinted with its vascular branchings. Next, the arachnoid, this transparent filmy membrane with its many large blood vessels. And finally, at the surface of the brain itself, the pia mater, the extremely thin surface covering of the brain, also a highly vascular membrane whose most fine blood vessels actually penetrate into the brain tissue itself. When I first started doing dissection, I was quite confused by the fascial and membranous wrappings of the viscera, and particularly of the cranium. I'd confused the arachnoid, which I'm dissecting away from the brain here with the pia, because I couldn't relate to the surface of the brain as a membrane in itself. The pia mater, though technically and histologically a membrane with different cellular properties than the nerve cells which it covers, doesn't really give the impression of a sheet or a fabric the way the other membranes we've seen do. The pia mater is only a few cells thick. You can't really peel it away. You can push your finger through it. It's so soft without much resistance. It nonetheless functions as a membrane, as do the skins of all the other large organs of the body. As I differentiate the arachnoid from the pia here, its large blood vessels come away with it. These vessels themselves are coated with the pia mater as well, just like the nerves which branch from the spinal cord. Further, the pia and the arachnoid are related through myriad fine trabeculae, which create a mesh between the two membranes through which the cerebrospinal fluid circulates. So the removal of the arachnoid along with these blood vessels is actually creating innumerable breaks in the continuous fabric of the pia itself. The pia follows all of the convolutions of the surfaces of the central nervous tissue, including, of course, the delicate and leaf-like infoldings of the cerebellum, here seen in cross-section with the arachnoid still draped around its outer surface.

From the looping tissue of the cerebrum, then, to the horse's tail and the tapering conus medularis at the end of the spinal cord, the soft and gentle mother, the pia mater, wraps and enfolds the whole of the nervous tissue with its tender covering. Unlike the first two volumes, this third part of the integral anatomy series involved a bit more technical vocabulary, so I've included at the very end, after the credit roll, a few charts listing the main terms which I've covered. The images are ultimately more important than the language, and to truly grasp and absorb this material, it will be worthwhile to view it several times over. Beyond even the images, integral anatomy is ultimately an invitation to an experience of the whole person. Bringing it to that level is a matter of introspection, shared reflection, and a commitment to self-responsibility for life experience. Joy is our birthright, the breath of life, a gift of the most profound order, and our creative potential is unlimited. There's always more to come. So the water water water water water water water water water water water water water water water water water