the spinal cord is part of the central nervous system and so like the brain and spinal cord
they are both covered with all three meningeal layers and this includes the dura on the outside
the next layer in which is the arachnoid and then the Pia the Pia mater which is just up
against the spinal cord and very difficult to you know peel off as we talked about when we talked
about gross anatomy and the nervous system in general so all three of these layers exist we
have a subarachnoid space just like we did around the brain we have a subarachnoid space around the
spinal cord the dura fuses with the spinal nerves out here and eventually the nerves are going to be
covered by something called epineurium which is a connective tissue layer which helps the
nerves maintain their integrity and keeps them from getting squished or pulled too hard but so
there's a fusion of those but the initial part of that spinal nerve is covered actually by the
dura mater itself and the next couple of slides we'll see some actual cadaveric images of these
layers within the spinal column within around the spinal cord within the vertebral column so
this is an image then of the actual spinal cord in situ with our Dura on the outside and then you can
see the arachnoid in this area with some of the nerve roots and blood vessels and then the pia
again it's so adherent to the spinal cord that we can't even peel it off you can also start to
see which is really cool some of these nerve rootlets in this area these little guys are nerve
rootlets and then here is the spinal cord in the vertebral column so within the spinal cord and
in the vertebral column the dura is just a little bit different than it is in the brain around the
brain the dura acts as periosteum and forming a meningeal layer and so it's right up against the
the bone and there's no basically hardly any space between the brain and the bone except
for that kind of that subarachnoid space so it's very tight within the spinal column as you know
from going over the musculoskeletal lectures the vertebra bend a little bit you've got a little bit
of flexibility in your vertebral column because it's not one solid bony structure its individual
vertebra that articulate with one another and so with regard to the dura in the vertebral column
itself there's a space and so the dura kind of comes down here and then all of the bones
are out here right and so in this zone we have what's called the epidural fat because the door
is not right up against the bone and there's some ligaments involved here too that that that hold
the bones together and the reason is because your court because the vertebral column is flexible so
if you think about it the skull doesn't move so the dura can be right up against it because
it's never going to budge and it and it wouldn't stretch or pull on the dura within the vertebral
column because the bones move and you want the dura to protect your spinal cord it's going to
form a sleeve around the spinal cord but it's not going to be attached to the bones because
the bones are moving and so you need space for that movement to take place and you don't want
your dura stretched or pulled in any of these directions when the vertebral column moves so
that's why there's a space and some epidural fat above the dura and in between that and
the vertebral bones the vertebral bodies the dura then continues down beyond the spinal
cord itself into to the base of your sacrum and it covers a round group of nerve fibers called
the cauda equina so the basic explanation is that when you are an infant your spinal cord
and your vertebral column are about the same length but as you grow your vertebral column
becomes dramatically longer but your spinal cord doesn't it becomes a little bit longer but not
dramatically longer so the bottom line is that all of those nerves that are attached and exiting out
between the vertebral bodies eventually have to get to their targets which are farther away okay
and so the nerves just keep growing it's not like you stretch them like a rubber band they just keep
adding more membrane and the axons keep growing but what the but the result is this band of orb
and this bundle of nerve fibers that now extends because it's got to still make it out between the
correct vertebral bodies and so we end up with this big bundle of fibers called the cauda equina
or horse's tail equine on horse the end of the spinal cord right here this little pointy end is
called the conus medullaris and that's basically your coccygeal levels of your spinal cord some
more basic things about the spinal cord before we get into any of the details of the gray and
white matter as if you draw a line across it the dorsal part of the spinal cord is sensory
the ventral part of the spinal cord is motor just general organization of the spinal cord you also
have a blood supply for your spinal cord you have one ventral artery that runs here in this kind of
the sulcus and it sends out branches kind of a corona of branches that then come in and feed
the spinal cord and you have two dorsal arteries and again these are going to come in and branch
and feed areas of the spinal cord so theoretically you could have a stroke in your spinal cord just
like you can have a stroke in your brain if any of these branches of these arteries are
occluded in summary what I want you to know for the assessment how many do regions is the spinal
cord divided into so if you know that that's a good thing what meninges are associated with the
spinal cord can you remember what a spinal cord enlargement is all about and then what are the
general functions of the dorsal horns and the ventral horns and can you explain to me what is
the cauda equina if you understand these concepts then you'll do very well in the assessment