Imagine if it was pitch
black in your room. Would you be able to walk? As long as nothing
got in your way, you'd probably be able
to walk perfectly fine. But why is this? When walking in a
pitch black room, you rely on your
sense of balance. You know exactly where
you are in space. You know whether or not
you're standing straight up or if you're sitting down. And as you're walking, you
know if your right foot is in front of your left
or if your left foot is in front of your right. So how is it that we know
exactly where our body is in space without actually
having a look at it? Well, this is known as our
sense of propioception. And proprioception is basically
defined as our ability to sense exactly where
our body is in space. In other words, this is
our sense of position. And this sense
actually originates from a bunch of tiny
little sensors that are located throughout our
entire body in almost all of our muscles. So let's imagine that this right
here is a muscle in your leg or in your arm. Let's just say it's
a muscle in your arm. So there's a tiny
little receptor in it, inside of the muscle. And this receptor will actually
go up to your spinal cord and then eventually
to your brand. And this receptor, if we
kind of zoom in on it, we zoom in on this receptor,
is sensitive to stretching. So as this muscle
contracts, so if I was going to lift
something really heavy, the muscle would contract,
and it would get thinner, so it would look like this. It would get a bit thinner. And so this sensor, which
is known as a spindle-- I'll write that down here. This is a spindle. This sensor can sense that the
muscle has been stretched out, and it too will also stretch. So it will go from
this conformation to this conformation. It will actually
get stretched out. And so we can draw a little
spring-like structure inside, which is actually
quite similar to what's actually inside the spindle. There's actually a protein
inside that gets stretched. When that protein
gets stretched, it fires a signal to the brain. This is the basic principle
behind proprioception. So we're able to tell
exactly how contracted or how relaxed every single
muscle is in our entire body, and this allows us to know
exactly where our body is in space. There's another
word that's commonly used to talk about
your body's movements. And this is known
as kinesthesia. So let me write that
down-- kinesthesia. And so if we talk
about proprioception to include your body's
position in space as well as your
ability to balance, so your sense of balance
would be included under proprioception,
kinesthesia is talking more about the
movement of your body. So one final way to
differentiate between the two is that proprioception
can be thought of as a cognitive awareness
of your body in space. So it's more cognitive. So one way to
think about this is that it's a little
bit more subconscious. So you're not always thinking
about exactly where your body is in space, exactly how you're
orientated, if you're walking, or if you're running. Your main concern isn't,
oh, I hope-- it might be, but your main
concern isn't I hope I'm not going to fall down. Pretty much your
sense of balance, your sense of position,
are pretty well taken care of by your
proprioceptive sense. So it's more cognitive. It's more something
that's under the surface. You're not overtly
thinking about it. On the other hand, kinesthesia
is a little bit more behavioral. And what I mean by
that is let's imagine that you're playing
golf or you're trying to hit a baseball,
constantly you're swinging. Sometimes you miss,
sometimes you hit the ball. But every single time you
actually swing the bat or swing the golf
club, your body is able to detect
exactly how it's moving. And so over time, if
you learn that, OK, if I move in this
certain direction, I'm able to hit the golf ball,
or if I move in this direction, I'm able to hit
the baseball, then over time, your body
is able to detect exactly what that
movement is and start to undergo that movement
more and more often. So you're able to
actually teach yourself exactly how you should move in
order to successfully complete whatever task is at hand. So that's just another way to
distinguish between the two terms. But just keep in mind that
proprioception and kinesthesia are not the same. So they are not the same. So I'll draw a big x here. But they do share
a lot in common. And what they do share in
common is inferring movement, and position, and where
your body is in space. And the big difference is,
just to kind of summarize, is that proprioception is
concerned with position while kinesthesia is
concerned with movement. And proprioception includes
your sense of balance, while kinesthesia does not.