YouTube Video Transcript

[Music] hello everyone welcome back to my channel in this session I'll be continuing with the development of the spinal cord where we will be discussing about the myelination and some of the common congenital anomalies so before you watch this video please do the session which I already done on the development of smile C for a continuity so uh first we'll discuss about the mation of the spinal cord uh the mation mainly happens in the late fetal period And in the first year of the postnatal period uh and we know the Moto neurons are mated first before the sensory neurons uh when we think about the nerves uh there is some part of the nerve which is lying within the spinal cord and some part which is emerging from the spinal cord right so the part which is lying within the spinal cord they are actually melinated by the oligodendrocytes whereas the spinal nerve which is emerging out of the spinal cord they are melinated by the swan cells and these both cells are the neurog cells are mainly derived from the neural crest cells so that's about the myelination now uh considering the different positioning of the spinal cord we uh we know the adult spinal cord is not um actually aligned along with the vertebral column right so in during the eighth week of intra um U development uh we can see that the spinal cord is in line with the vertebral C but then later what happens by around 24 weeks what happened is the vertebral column is actually getting elongated but the spinal cord is not getting elongated like the vertebral column so what happens is the lower limit of the spinal cord is up to the level of S1 at 24 weeks now by the time the baby is born we can see that uh the vertebral column again uh the differentiation of the vertebral column is more compared to that of the spinal cord and the spinal cord is staying as s and the lower limit of the spinal cord will be corresponding to the level of third lumbar vertebra L3 now adult position is the lower limit of the spinal cord will be against lying against L1 vertebra so that is the final position of the spinal cord uh so in the initial period we can see that the spinal nerves will be uh emerging corresponding to the uh vertebra isn't it but what happens during the adult period the vertebra which was corresponding to the spinal cord in the embryonic period has shifted its position down so the spinal nerves has to make it have to make its exit by traveling down vertically then uh laterally so that process leads to the formation of Coda equina so Coda equina is nothing but the group of nerves starting from the lumbar region then the sacral nerves the coxy nerves along with the philm terminale which is nothing but the pile extension so all together it looks like a host tail and that is known as Cod equin the reason for COD equina is the differential growth of the vertebral column so in the beginning the spinal nerves were making its exit corresponding to the vertebra and they were just exiting laterally but uh During adult period because of the difference in position of the spinal cord and the vertebral column they have to travel down and then make its exit and that is actually resulting in the formation of Corda equin now uh something about the congenital anomalies of the spinal cord we call it as neural tube defects and that is mainly uh occurring when there is failure of fusion of the neural tube or the structures which are covering the neural tubal portion uh and that happens usually by fourth week so what are the coverings of the neural tube we have the meninges which is the immediate covering of the SP spinal cord then we have the vertebral large the vertebra lar portion of the vertebra then you have the muscles over it and then you have the skin over it so any issue with these coverings can result in a condition known as spina bifida and the severity of spinal bifida uh will be very less if only the skin is involved and the severity increases uh when all these neural large elements are involved so let's discuss the different patterns of spinabifida spinabifida is a favorite short note for ug as well as PG so you should know the concept first okay so what is spinal dermal sinus spinal dermal sinus actually occurs at the region of codal neuropore by around fourth week and what is spinal dermal sinus it is actually nothing but uh the surface ectoderm and the neural tube will get detached uh at that point sometimes this Detachment won't occur and the surface ectm will be attached to the neural tube that last point of attachment of the neural tube with the surface ectoderm uh if it is not getting detached you get a sinus at that point and that is known as spinal dermal sinus and it is usually silent without uh any issues for the spinal cord now we will see the different varieties according to the different elements of the neural AR involved the first one is spina bifida Ulta Ulta means we know that uh the issues with the spinal cord is actually hidden uh and instead you will be seeing a tuft of hair in the region of L5 and S1 so what is happening here the component which is involved here is the vertebral Arch vertebral Arch means means the part of the vertebra which is covering the spinal cord in the vertebral Canal so that part is defecting so the vertebral Arch Fusion has not occurred but the spinal cord the covering manages everything will be intact and safely secured uh so uh it will be seen uh to the ex for the external appearance will be just a tuft of hair in the region of L S1 and in very rare cases the spinal cord beneath and the spinal nerve Roots may be involved the next one is spina bifida cystica so what do you mean by spina bifida cystica apart from the vertebral Arch if you have the menes or the spinal cord protruding through the vertebral Arch it will be seen as a cyst so that is known as spina bifida cystica and according to the involvement of the manes as well at the spinal cord it is again subdivided as spinal bifa with meningo and the other one is sp spinal bifa with meningo milil so spinal bifa with mosil is again not that severe why because through the defect in the vertebral Arch you have just the menes protruding out but spinal bifa with meningo mosal you have a part of the spinal cord also protruding out along with the menes through a defect in the vertebral Arch so this is more serious compared to that of the SP spinabifida with Mingos now there is one antiy known as Meo enil so in Meo enil um usually when we discuss about the spab cystica and all only the lower part that is the region around Al and S1 is involved but when we discuss about Meo en several vertebrae will be involved and sometimes there is also partial absence of the brain as such so this is more severe compared to the other two conditions now uh usually we can detect the neural tube defects by an elevated level of alphao protein um in the amniotic fluid of the mother and the by around 12 weeks if you do USD it is said that you can visualize the vertebral column of the fetus so around 12 weeks if you do USD uh any the severe conditions like Spina B cystica can be always detected now there is a very very severe condition of the spab bifida that is known as myo chis that is this is the most sever severe form and what do you mean by myosis here what happens is till now we were discussing about the coverings of the neural tube the neural tube has actually closed and there is no issue with the neural tube but the coverings of the neural tube we were discussing and if defective it results in spinabifida but in myisis the neural tube itself is not closed so what will happen the spinal cord will be just seen as a flatten mass and sometimes it will be exposed to the outer aspect or sometimes it will be just covered by a thin membrane or skin and that is very very severe and uh the affected person will be having severe problems and now what are the uh eological factors which lead to neural tube defects uh the first and foremost is folic acid deficiency and that is the reason why we actually uh administer folic acid for uh ladies who are planning to become preg pregnant that is mainly 3 months before they plan to conceive and it will be continued uh till the uh third month of uh pregnancy because the neural tube development happens mainly in the first trimester now uh intake of valproate that is also related with the neural tube defects and increased vitamin A intake is also connected with the neural tube defects now I will just sum up we have seen the myelination um the igod dendrites and role of schanell then the positioning of the um spinal cord uh the changes in position from 8 week till adult period now uh the neural tube defects um what are the factors Rel causing neural tube defects as well as the different variants of spino bifa uh so keep watching and please let me know whether it is useful for you and I would also like to uh mention about ancal 2023 uh the details will be uh shared in the YouTube thanks for watching