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hi everybody and welcome back to miss
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Angler's biology class I am Miss angler
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and in today's video we are going to
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cover the human skeleton specifically
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the axial skeleton in a follow-up video
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I will be covering the appendicular
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skeleton now if you're new here don't
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forget to give this video a thumbs up
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subscribe turn your notifications on
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because I post a video every Tuesday and
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Thursday for grades 8 to 12 Life
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Sciences or biology
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now we're focusing in today's video on
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the axial skeleton and the two major
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components of the axial skeleton is the
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skull as well as the vertebral column
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I'm going to go through all of the bones
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you need to know how to tell the
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difference between them as well as how
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to label a skeleton if you were to get
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one in an
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exam so let's begin with the scull now
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it's really important for everyone to
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know that this entire structure
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collectively is the skull everything all
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the smaller bones that it is made out of
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and often we don't know that there are
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sections to the skull that have
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different names the first section of the
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skull I want to talk about is this top
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area over here along with the Dome at
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the back that over there is your cranium
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and so your cranium is the casing that
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sits around your brain the next bone I
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want to focus on is this one over here
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it is the bone that sits around your eye
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it is called the zygomatic bone in some
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textbooks it calls it also the orbit
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bone as well the next bone that we have
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inside of the skull is called the
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maxillary bone also known as the upper
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jaw bone this is the uh part of your
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Jawbone that doesn't move it's still
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it's static the lower portion of your
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jaw this bit at the bottom here that you
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can move is known as the mandible um and
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the nice way to remember the difference
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between maxilla and mandible is mandible
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is movable it is the movable part of
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your jaw you can't move the top part of
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your jaw that's fixed in
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place now if we look at some specifics
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about the cranium you'll notice that the
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cranium has these like squiggly lines
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through them and what they are they're
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not fractures um in the cranium they are
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what we call sutures they're basically
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where your bones have fused together as
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you've aged and the reason for that is
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your cranium is in pieces when you're
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born it's not completely solid um so
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that you can move to the birth canal a
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lot easier now these different regions
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of the skull also tell us the regions of
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your brain there's a nice little overlap
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if you know um the name of the bone that
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part of the cranium you also know the
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part of the brain and so first of all we
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have this front portion of the cranium
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which is known as the frontal
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bone then we have the uh top major side
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area of your head here which is the
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pericial part of the skull we then have
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uh this bone sitting on the side here
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called your temporal bone uh where your
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temples are the sides of your head and
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then the final bone is this back part of
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the bone here which is is your occipital
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bone I know that's so weird because
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occipital means eye it's because
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actually the point at which your eyes
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connect to your brain is actually at the
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back of your brain um and so those are
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all the labels that you will need to
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know for tests and
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exams right then moving on to the
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vertual column the vertual column is
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divided into five major regions starting
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off with the first seven sets of bones
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at the very top which is the cervical
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bones and we label them C1 to C7 then
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beyond that we have the thoracic bones
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um and there are about 12 of them so one
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two three four five that's where it cuts
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off over there um and these are numbered
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1 to 12 then below that you have the
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lumbar region which is your biggest
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vertebrae and then you have a divide
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that's sits sort of at an angle here
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that is your sacral bones there are five
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of them down here and then this teeny
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tiny little bone right at the bottom um
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is your cockail bone and it is made up
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of four bones you'll notice that the
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sacral bone and the cagal bone just have
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the number four and five that's because
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those bones are fused together so we
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just count them as five bones that make
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one very big
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bone the next important step about the
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vertual column and the vertual bones is
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we need to know their structures and you
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are looking at a typical vertual bone um
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I'm going to go through the specific so
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how to tell the difference between them
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soon but there are some important labels
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and things that you need to look out for
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when you are trying to label this first
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of all um a key thing to look for is the
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spinous process this is this little
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pointy bit out at the top that actually
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tells you a lot of information it tells
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you which kind of vertebrae you're
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looking at is it long is it short is is
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it not there at all that will definitely
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tell you which bone you're looking at
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and also this is the little bone that
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sticks out your skin it's the part of
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the vertebrae that you can feel the next
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important part of a vertebrae which
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tells you which uh vertebrae it is is
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also known as the body or the Centrum
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they're both correct and basically it
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refers to this entire um back portion of
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the bone it's where the majority of the
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body weight is also pushed through in
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that area then we have something called
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the transverse process and the
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transverse process uh refers to these
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like little uh elongated pieces of bone
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that go off to the left and right sort
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of look like little wings on either side
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then you have something called the
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articular processes um and the facets
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and essentially what these are if I put
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them in a different color you have uh
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two on either side over here you've got
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two on the ends of your transvers
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processes and you've got actually two at
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the back here all of those facets are
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for other bones to rub up again they
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might be there for ribs they might be
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there for other vertebrae to rub up
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against and that's their purpose to make
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space for other Bones the next important
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component of any vertebrae is to make
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space for the spinal cord and what we
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have here is the vertebral Arch and the
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vertebral fmen and fmen means like a
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hole where a nerve can pass through so
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the arch is the arch in the bone and
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then the fmen is this hole in the center
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that's where the um spinal cord will
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move through and um in some textbooks
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they call it a neural Arch and a neural
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Canal those are both correct as well now
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also depending on your level of
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Education in terms of like what grade
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you are if you're watching this video
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but also what type of um education
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you're doing ieb or NSC you might need
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to know a few more labels and so I'm
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just going to go through these other two
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which is the lamina which is these walls
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at the top here of the arch and then the
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pedicle which is this joining part of
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the bone so the lamina and the pedicle
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both form like these joins between the
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transverse process the spinous process
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and the
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Centrum so let's look at the first two
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cervical vertebra they are one of the
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most important pairs of vertebra because
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they allow you to have full mobility in
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your neck and they enable you to nod
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your head and also um turn your head and
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rotate your head and we're going to
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start off with the atlas bone which is
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this one over here and uh the atlas bone
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has these lovely articulating surfaces
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they're very very very large on either
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side here and that's basically where
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your skull uh rests upon your vertebral
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columns they're going to be quite big
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and then this Center area over here the
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neural um Canal is very very large and
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that's because the spinal cord leaves
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the brain first through this opening so
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it's the biggest part of your spinal
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cord now when it comes to identifying
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the atlas bone in a diagram there are a
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few things I want you to look out for
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when we're identifying it we're looking
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out for the fact that it's not going to
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have a Centrum it's missing that big
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chunky round bottom bit um and the next
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thing you're going to look out for as I
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just pointed out earlier was the
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articulating surface is quite large it's
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that big blue area I've highlighted the
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last thing is it has the largest Canal
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it has the biggest neural Canal or
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vertebral Canal that runs down the
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middle there with the fan being the
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biggest if you compare it to its
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neighbor you can see it's much smaller
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and speaking of its neighbor let's move
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on to the next bone here which is the
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axis bone so this is the second cervical
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bone now this cervical bone uh is very
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important because it allows you to
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rotate your head so the atlas allows you
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to nod and the axis allows you to rotate
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and it's also got some key features
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which are slightly different to its
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neighbor first of all looking at this
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tip of the bone here this is the spinous
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proc the next notable feature is these
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large articulating uh parts of its bone
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over here which is where again these two
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articulating surfaces rub up against its
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neighbor because this is the first bone
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of the vertebrae it sits on top of the
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axis which is the second bone and so you
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need this big area for it to sit on top
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of that and the final thing that makes
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it very unique is this structure here
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which is not so clear when we look at
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the bone from the top so if we look at
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the bone from the side um what we are
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looking at here is this pointy bit over
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here in the bone actually sticks all the
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way up that is called the odontoid
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process and that is the thing that
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allows you to rotate your head it allows
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your um Atlas to spin or move and rotate
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around it now when identifying the axis
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we're looking for the following things
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first things first we are looking for a
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forked spinal process we're looking for
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that peg-like odontoid process as I just
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pointed out now it doesn't have any
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transverse processes so it's missing
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those little side wings they're not
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really there and it also has quite a
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large neural
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Canal now we're moving into the three
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other components of your vertebral
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column I'd like to point out that the
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atlas and the axis are cervical bones um
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and so the rest of the cervical bones
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are just standard cervical bones there
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nothing special about them but their
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shape does change an alter over time and
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so what you see in front of you here are
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the three other varieties that you get
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we have the cervical bone over here the
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thoracic bone and then finally the
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lumbar now um in terms of what you're
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looking for and to tell the difference
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there are some key things that you need
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to ask yourself when you're trying to
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tell the difference between these bones
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and the test or an exam the first thing
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you're going to look at is is there a
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Centrum so what's the size of the
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Centrum and then is it even there or not
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now in these three bones they all have
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which is this area of the bone down
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here
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but they're all different sizes and in
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the atlas and the axis they're both
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lacking it so if there isn't a Centrum
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it must be the atlas or the axis but for
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the rest of these there must be one of
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them and you'll notice that the Centrum
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gets bigger as we go down the spinal
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cord the next thing you're going to look
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at is the neural Canal so the size of
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the neural Canal now the size of the
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neural Canal does get smaller and
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smaller as we go down it's a little bit
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deceiving in this picture um because the
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middle one looks the smallest but in
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actual fact it's the second smallest so
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generally we start off with the biggest
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neural Canal which is true this is the
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cervical bone which means it's closest
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to the spinal cord coming out of the
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head then we have the thoracic which
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this is a little bit deceiving it makes
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it look a bit small and then the Lumar
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technically the lumbar should have the
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smallest hole um because it's the
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furtherest away from the spinal
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cord or should I say it's the furtherest
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from where the spinal cord leaves the
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brain through the SK well the next thing
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that you're going to look at and this is
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more of a cheat sheet everybody this is
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not something that I would write in an
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exam like I wouldn't write this down as
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a reason but I would use this to tell
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the difference um thoracic vertebra
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generally have more of a vshape to them
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let's just go over that with a darker
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red a
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vshape to their transverse processes
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whereas a lumbar have more of a t- shape
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to them and so that's like one easy way
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to identify them which brings me to the
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third point the transverse process is it
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present or absent in cervical bones like
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this one over here alongside there is no
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transfers process if you look here
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there's nothing there there's nothing
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sticking out however in the thoracic and
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Lumbar is there and as I mentioned now
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you can look for the two different
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shapes to tell the
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difference the final component of the
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vertebral column is the sacral and cagal
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bones and when we talk about the sacral
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bones we're talking about this region at
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the top top here um and the sacral bones
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are actually fused bones so it means
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that the bones are stuck together
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they're not like individuals you can
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actually see the fusion lines going down
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through here and then the second set of
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Bones which is this lower portion at the
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bottom over here is called the cockail
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bones we often like call these the coxic
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bone or the tail bone and that again is
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fused bones at the bottom and you can
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see them fused here together
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so let's go through a terminology recap
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because there was a lot of terminology
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as you can see and please use these
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words for your flash cards when you're
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studying so we're starting off with the
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axial skeleton which is made up of the
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skull um as well as the vertual column
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the vertebra and um the skull is made up
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of the cranium the zygomatic um bone or
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the orbit bone the eye bone uh the
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mandible so the upper jaw sorry the
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lower jaw the maxillary which is the
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upper jaw and then I spoke about
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something called the foran Magnum which
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is the opening in the skull where the
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spinal cord leaves the brain we then
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spoke about sutures which are the joints
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in the skull the frontal
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pericial uh temporal and occipital are
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all um regions of the cranium bones that
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are divided by sutures when we looked at
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the vertebra we looked at the cervical
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bones they were the first set of Bones
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specifically the atlas in the axis that
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allow you to rotate and Nod your head we
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looked at the thoracic the lumbar the
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sac and the cockail those are all
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different types and you must know how to
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identify them and also we looked at of
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course the general structure of the
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vertebra the Centrum the neural Canal or
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the
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fan um the transverse process spinous
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process and lastly the articulating
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surfaces which is where your bones
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articulate against each other either the
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ribs articulating with the vertebral
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column or another vertebra on top of the
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other one and they move up against each
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other now if you like this video don't
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forget to give it a thumbs up and
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subscribe and turn your notifications on
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the followup video to this will have the
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appendicular skeleton in it and I'll see
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you all again soon bye
