 Good day everybody. This is Dr. Sanjay Sanyal, Professor of the Department Chair. This is going to be a demonstration of certain dissection specimens of the spinal cord. So we have removed the occipital bone from here. This is a prone cadaver. We have done a post chest for saccharinectomy. And then we continued down and we also removed the paraspinal muscles. We removed the laminate of the cervical vertebrae from the cervical thoracic, lumbar, sacral, and then after we have split the dura to show the spinal cord. In an earlier dissection, we had mentioned the upper part of the spinal cord and the spinal nerve roots and many other features here. Now we shall focus on and we shall go right up to the bottom of this dissection to show you the lower part of this dissection. We have, as I mentioned, we have split the dura and the arachnoid. And we have reached the lowest part of this dissection at this region that we can see here. This is referred to as the lumbar cistern. What's the meaning of the word lumbar cistern? Lumbar because it's in the lumbar region. It extends from L2 to S2, vertebral levels. Cistern means an enlarged subarachnoid space filled with CSF. What are the contents of this lumbar cistern? The contents of the lumbar cistern, as I mentioned, one is CSF. The second important content, of course, are these multiple branches that we can see here. These are the branches of the lumbar sacral and the coxigel nerves, which is referred to as collected with the corda equina. The third content, of course, will be a small structure which we cannot see, which is a non-neural structure called the phylum terminale. This is the T2-sidiacal MRI, the lumbar region to show the lumbar cistern, the CSF, the corda equina, and the conus medullaris. And this is a lumbar myelogram AP view to show the lumbar cistern, the conus medullaris, and the corda equina. Now let's see a few quick words about end of the spinal cord. End of the spinal cord is here. It is located in this region. This is referred to as the conus medullaris. The spinal cord ends approximately at the upper border of L2 vertebra and it is also referred to as the medullary cone. This conus medullaris, we can have an important syndrome here and that is referred to as the conus medullaris syndrome. That happens when there is any one of the intradural tumors like, for example, appendiboma, astrocytoma, or we can have HIV lymphoma, or we can also have arterial infarction of the region of the spinal cord. Incidentally, fracture of L1 vertebra can also produce the same syndrome L1 vertebra refers to this region of the spinal cord, which is the sacral of the coccygeal segments. When there is a compression of this region of the spinal cord, the segments which are involved are the S3 to CO segments, sacral third to the coccygeal segments. Usually the manifestation will be suddenly a non-sit and it will usually be bilateral. Manifestations will be more severe pertaining to the parasympathetic portion that is the bowel bladder and male sexual mechanism namely importance because the S2-3-4 segment is important for migratory center, defecation center, and the male erection in the ejaculation center. That is referred to as the conus medullaris syndrome. We can get another syndrome which refers to the portion above that and that is referred to as the epiconus syndrome which extends from segments L4 to S2 which can also be caused by pretty much the same causes and the patient will have very severe difficulty in extension and lateral rotation of the hip joint because of the paralysis of the gluteus maximus muscle. Additionally, the person will have weak anchor jerk which is root value with S1-S2. So that's about the conus medullaris syndrome and the epiconus syndrome. Now let's talk a few quick words about the cauda equina itself. This cauda equina looks like a tail of a horse that's why it is called cauda equina. The cauda equina can also be involved by medius tumors, intradural tumors, they can be nerve root tumors, lipoma of the cord, dermoid, neurofibroma, and it can also be caused by HIV lymphoma and rarely it can be caused by a central herniation of the nucleus pulposus of the lumbar vertebrae. This is a T2 MRI of the spinal cord showing an HIV lymphoma in the region of the cauda equina. The cauda equina syndrome usually occurs gradually and it is usually somatic symptoms will be more severe in the sacral saddle area. Saddle area refers to the area which a person sits on on a saddle and usually it is unilateral more common than it is bilateral. So there will be severe pain and there will be muscle weakness in this region. So that is heavy saddle anesthesia and heavy saddle muscle weakness. In contrast to the conus medullaris syndrome, the bald bladder symptoms, the autonomic manifestations will be very few or very limited. There is yet one more condition which in this is not visible and that is called the phylum terminal. The phylum terminal is a neuroglial tissue which extends from the conus all the way down through the lumbar cistern and it then pierces the dural sac and it goes and gets attached through the sacral canal to the coccyx. That phylum terminal has got the internal portion which is called the pial part and an external portion which is referred as the dural part. In a small percentage of people the phylum terminal can be very short thick and stout and it can pull on the lower part of the spinal cord and that is referred to as the phylum terminal syndrome. It can produce again symptoms pertaining to the lower part of the spinal cord that is the patient will have lower motor neuron bald bladder symptoms and will have also have weakness of the sacral region, the weakness of the ankle jerk or the phylum terminal syndrome and it may require transection of the phylum terminal. This same phylum terminal if it pulls hard then it can also produce traction on the upper part of the spinal cord and can produce downward displacement of the medulla through the ferrimid magnum and that is referred to as herniation syndrome. I had briefly mentioned that when I was talking about supra dintorial compression. This is a T1 sedatum MRI to show cerebellar vermus herniation through the ferrimid magnum in a case of anodicary malformation and this is a T1 sedatum MRI of an anodicary malformation to show cerebellar vermus herniation. So therefore this condition is referred to as a tethered chord syndrome. So these are the few quick points which I want to mention to you about the three regions that the clinic of significance, the lumbar system, the cauda equina, the conus medullaris and the phylum terminal. Thank you very much for watching Dr. Sanjeev, Sunny and Sunny out please like and subscribe if you have any questions or comments please put them in the comment section below have a nice day.