Understanding: Pivotal and Hinge Joints Video Lecture | Science for Grade 6

hello friends this video on body
movements part 7 is brought to you by
example calm no more fear from exam the
next type of joy it is the people till
joined here one goon who votes within
another body that forms a ring so here
as you can see you have one bone which
provokes within another bony structure
like this that forms a ring it is a ring
like structure now this other goal it is
let's call this goal number one and
that's why the structure has - so now
border for one and actually slide over
this ring bony ring like structure so
because of this now this ring is not a
complete ring right so this half ring
can easily be covered by the first bone
so therefore it can actually move or
slide over this ring which allows a
rotating movement around the single axis
so that single axis will be this axis
and around in this axis it can actually
move back and forth so the moving bone
rotates within this ring so it allows
only door to be movement so it will not
allow any other type of movement so like
unlike the ball and socket joint where
any type of free movement is allowed
here the movement would be limited only
rotary movement will be allowed so let's
take an example like when we turn on
head from side to side or when we turn
our head from front to back that is down
and up what happens so that turning is
like you do not turn it complete
you cannot turn your head completely
language complete rotation is not
possible but we can definitely rotate it
this way again this way this way and
this way so basically a rotate rotary
movement but it is not complete rotation
it is partial rotation that is because
of this bony structure which is present
with this bony structure will only allow
half rotation so this kind of movement
is due to the presence of a people joint
where the neck and the head is joined so
that is why we have this type of
movement at our neck
so this is an example of people to join
in fact this is how it works
so basically you see that every type of
joint we have spoken about three basic
types of joint one is fixed joint where
no movement is allowed next is paddle a
chain will join when limited movement
azar out like the backbone and the third
one is to know we are trying to bed good
amount of movement is our output in
synovial joints also some joints their
structure is such that they allow
considerably more movements whereas in
case of some other joints the structure
is such that they allow it in the mitad
movement so by looking at these examples
you can get an idea ball and socket
joint is a completely flexible it allows
any kind of free movement we would enjoy
little less flexible so it only allows a
rotary movement now as we move ahead and
go to the hinge joint we say that human
bones can move only around one axis
depend on extent so then here are the
bones can only bend and extend for
example think of the scenario when you
open a door so how the door moves so the
door and actually either go this way or
this fit so we can just move at an angle
Samantha maybe could be this much not
more than that right so basically from
here to here it can move at any angle
but it can only extend or bed that's it
it cannot rotate either partially or
fully so this type the best example of
hinge joint would be the kneecap so at
the knee also you see from me we can
make our knee straight we can bend it so
that's all that is the only way we can
move our knees so these joints are
formed between bones such that the bones
can move only along one axis to extend
or to bend so it only allows back and
forth movement so if you take the
example of our meal so we can make our
knee like this while kicking a football
we can also straighten our D like this
so basically we can move it from this
angle to this happen so earlier it was
like this so you see and only at this
angle we can either bend it or we can
extend it so when we bend it like this
we call this as flex on flex means to
then to contract so that is Nexon and
then we extended like this that is
called extension so whenever it comes to
again joint it causes a movement which
is either an extension or a flexion flex
on so let's look at some examples which
will make it more clear so think of
elbow so from the elbow again you can
either make it straight which is nothing
but extension or you can bend it or you
can fold it so that is nothing but
flexion so these
movements that you can do with your
elbow so wherever you are extending it
that's extension whenever you are taking
it towards you that's flexion me so me
also using that what is this this is
extension but when you look at it you
are folding it so that is clicks on
think of ankle
so for ankle also when you make it like
this that is extension and when you fold
it this way that is flexion so each of
these are examples of hinge joint so
whichever part of your body you feel
that you can move it only back and forth
you can have to rotate it at all so they
are all examples of hinge joint so when
you look at these examples you see that
these type of joints the hinge joints
especially there two bones are connected
in such a way that either the bones
would come near each other that is they
would try to decrease the angle between
neck all the goons would move away from
each other so when they move away from
each other then we call this as an
extension and when they come towards
each other we call it as a flexion so
one very good example would be the
joints between the bones of fingers or
toes so they're also the bones are able
to flex to decrease the angle between
them so if you look at the distance
between your fingers do you think that
you can
Englishman you can just bang your
fingers to increase the distance or
increase the angle between them that's
all you can do the limited amount of
movement is allowed so that is also an
example of ninja joint thank you please
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