hello anatomy colleagues this is dr alsup and i am ever so excited to be in neuro with you so
we can talk about the anatomy associated with neurology we are going to start our discussions
with this video on the cranial meninges and hopefully you recall some of the details regarding
the meninges because we did discuss meninges when we discussed the spinal cord as meninges
are associated with both the spinal cord and the brain and they are continuous with one another and
the cranial meninges as well as the spinal meninges will share many many similarities but
there are a few a few distinct differences between the two and we will talk about that as well so
as a review there are three membranous layers that surround the central nervous system and recall
that the central nervous system is composed of the spinal cord and the brain our focus
for these upcoming learning objectives will be the brain
the major function of these layers is really to support and to protect the central nervous system
and there's going to be three main layers from superficial to deep there is the dura mater
which is going to be the most robust it literally means tough mother so when we do the craniotomy
you will see it will be the first thing you see is quite opaque and very obvious
now there are two layers associated with the brain of the dura mater and that's where this
big difference comes between the two as there's only one layer of dura mater
associated with the spinal cord so more to come on these two layers and some upcoming slides
and you can see just before i move on you can see here the two layers of the dura mater associated
with the and this is brain here okay next or intermediate will be the arachnoid mater which
is much thinner than the dura and is adhered to the dura mater but separated from the pia mater by
all these spider-like trabeculae that are going to be found throughout the subarachnoid space this is
actually um where the arachnoid gets its name are these kind of spider web like arachnoid trabeculae
lastly there is the pia mater which is extremely uh closely related or very intimately related to
the brain and the vasculature that is on on the brain it is transparent it gives
kind of the shiny appearance that you'll see associated with the central nervous system
okay let's talk a little bit more about this cranial dura and it's two separate divisions
as this is unique to the cranial dura but let's start with the basics
so there is going to be first and foremost the periosteal dura mater and i'm going to kind of
outline the periosteal dura mater right here put a P the pair and i know that this is the periosteal
dura because right here this handy dandy label that says bone the periosteal sometimes
referred to as the endosteal dura will line the cranial cavity so it's actually adhering
to the internal surfaces of the bone there's not a space right here
with the meningeal layer which is the the deeper more inner layer of the dura mater
this is going to be closer to the neural tissue and closely applied to the arachnoid mater so
here is going to be the meningeal dura kind of outlining it right here we'll talk about some
of these dips in a moment in certain areas the meningeal layer will actually reflect
inward as you can see occurring right here creating what's referred to as dural partitions
or dural infoldings and we will discuss this in quite a bit more detail in the next slide
now in other areas so not as you can see here in this image but in a lot of areas that periosteal
meningial dura will actually be very closely adhered but in certain areas they will separate
from one another in order to allow for deoxygenated blood to flow through regions
and these regions are called the dural venous sinuses so that's what all of this blue is
right here the superior sagittal sinus is a venous sinus we will have a whole learning
objective video regarding the dural venous sinuses so more to come on that i promise
but before we finish i do want to talk a little bit more about the dural partitions these form
partial partitions or compartments throughout the cranial cavity and they're going to be located
in between specific parts of the brain and because and kind of because of this organization it really
serves to provide additional support in this area there are actually four dural partitions
but we are going to focus on the two largest and so starting with the falx cerebri which is
actually the largest i'm going to kind of outline kind of the the basic area of the
falx cerebri with my very kind of wiggly line it's going to be located in the longitudinal cerebral
fissure so it's actually in the sagittal plane between the cerebral hemispheres
so that longitudinal fissure is going to be located between the two cerebral hemispheres
the brain's been removed in this dissection but you would have one cerebral hemisphere
kind of facing you and one on the other side of the fox cerebri
it's this very distinctive sickle shape and you it will actually house both
the superior and inferior sagittal sinuses so one of those sinuses has
been open here that's that superior sagittal sinus running right there
the second largest is going to be the tentorium cerebelli and you can see this is the tentorium
cerebelli here it's more transverse in orientation you'll have a similar component of it on this
other side as well on the right side and the tentorium cerebelli will separate the cerebrum
from the cerebellum all right so very close names but this so it will separate the cerebrum
from the cerebellum so in essence separating the forebrain from the hindbrain
it also creates this notch which i'm going to outline here referred to as the tentorial notch
which is the um internal or anterior concave border of the tentorium cerebelli and this
is actually where the midbrain will sit so the cerebellum would be kind of deep to the tentorium
cerebelli and the cerebrum will be more superior in certain pathological conditions like brain
swelling or with space occupying lesions portions of the brain such as say like the temporal lobe
of the cerebrum which is not too far away from the tentorial notch will actually herniate into
the tentorial notch this is tentorial herniation and what that will do is compress the contents
in this region so as we just discussed the midbrain is going to sit in the tentorial notch
and it can affect some of the neurovascular structures associated with the midbrain such
as the oculomotor nerve which is cranial nerve three um the posterior cerebral artery is also
going to be in that general area so if you have that compression of these structures that can
have implications in different presentations all right we have reached a summary slide
which i hope will be helpful to consolidate these high-yield concepts we discussed here thank you
for your time and attention and please feel free to reach out with any questions have a great day