Hey everyone, Sinix here.
It's time for another episode of Anatomy Quick Tips,
the series that is here to give you some useful observations
and help you feel more comfortable with
drawing people from imagination.
Today, we'll be talking about arms -
and also, don't be alarmed but
this all-arm video puts us near the end of this series,
only two more videos remain.
Regardless, for now let's just focus on these upper appendages.
This probably won't be the funniest video in this series or anything,
but it will be definitely be the most humerus -
so roll up your sleeves and let's get to work.
Starting out with structure,
we've already covered both shoulders and hands
in other videos,
so we just need to make sure we can bridge these things together.
I'm sketching a quick front, side and back view of a shoulder to start.
Seeing a shoulder and torso without the arm
always reminds me of a little lamb or something...
but anyway, we're going to focus on
the skeletal breakdown of the arm first.
Of course we have a single major bone
in the upper arm
and two in the lower arm
connected at the elbow.
But as i draw that, the first thing I actually want to point out
is that things aren't in a perfect straight line.
You can even take a moment
and try to see this yourself -
just hold one arm out straight
and close your opposite eye.
Now do your best to look directly straight down
the barrel of that massive gun you call
your upper arm.
If you line up your sight from shoulder to elbow,
you'll notice the lower arm doesn't really
line up as much as you might've thought.
To get really good at drawing any organic forms,
it's important to try and identify these types of subtle offsets
as much as possible.
Anyway, let's get back to these bones.
The humerus is of course the bone
of the upper arm,
meanwhile the lower arm has the ulna,
which I would consider the primary lower arm bone.
It's the one you would be hitting someone with
if you elbowed them.
And then the radius, which originates
on the exterior side of the elbow
A.K.A the side that's further away from your body -
and always connects to the thumb-side of your hand.
So we can do a bit of a rotational twisting
around the lower arm.
Hence the name 'radius'.
The last skeletal thing I want to mention
is the funny bone.
This is just an extension of the humerus
which protrudes on the inner side of the elbow
closest to the body.
It's called the funny bone
because of an exposed nerve ending next to it
that will send a shock up your arm
if you hit this part of the elbow against something.
So if you ever see a chance to whack
your friend's funny bone with your pencil or stylus
it's, you know, free comedy.
Alright, I added some hands to these drawings,
and I know this isn't the hands video
but since wrists and organic offsets are so important,
let's do a quick look at that connection anyway.
Now keep in mind by the time
the radius and ulna get to the wrist
they'll always be side by side,
and therefore the lower arm connects in
a much flatter and wider way into the palm
and back of hand,
and thinner from the side view of the hand.
Basic stuff, but the fun part is
any time you're adding a hand to an arm,
make sure to give it a bit of an offset
and step over toward the thumb/radius side of things.
Similarly, from the side view the hand should always
take a noticeable offsetting step toward the palm side.
By the way when I say the word 'offset'
it usually just means not lined up evenly with surrounding things.
Anyway, always make sure the thumb side of the hand
feels more chunkier and substantial
than the pinky side of the palm.
With all of these ideas in mind,
you should be able to develop a quick shorthand
for getting from the arm into the hand.
In fact, you should be able to
quickly deduce everything about the bones
and orientation of the wrist without ever seeing
the thumbs or fingers or any interior information.
So maybe see how quickly you can determine
where the radius and the ulna are
in any of these rough sketches I'm making.
Hopefully that seems easy enough.
Let's get back to structure and talk about the muscle side of things.
We're going to make it really easy
for our drawing purposes
and only focus on three muscle groups.
The biceps are on the front of your upper arm
and allow you to curl up your arm.
They insert under your shoulder muscles and chest muscles on one end
and connect to the radius and tissue around the ulna on the other end.
The triceps are on the back of your arm
and allow you to pull your arm straight.
They also come out from under your shoulder muscles and similar back muscles
and connect to the end of the ulna.
And yes, the deltoids are of course the shoulder muscles,
but the third muscle that we're going to be fixating on in this video
is going to be the brachioradialis.
You must learn to love the brachioradialis,
it will be a pivotal part of this video in more ways than one.
These insertions points are important, so keep them in mind.
It connects from the lower back of the humerus
under the triceps and it wraps around a bit
over parts of the lower biceps and
connects to the radius on the other side.
I will be exaggerating this muscle heavily throughout this video,
so be aware of that strategic inflation.
We are going all in on the bray-ray.
I think that's enough structure though, so
let's get into some drawing practice.
A big theme in the land of arms will be
controlling our organic curves.
So I guess I will do a quick recap on s-curves and c-curves.
Don't let the names throw you off too much,
most of the s-curves and c-curves you'll be drawing
are going to be extremely subtle.
Just a whisper of curvature going on most of the time.
And it's good to practice that level of control
but an even more important thing to practise
is your ability to weight your curves.
Weighting a curve means changing up
the harshness of the curvature through the line.
So if the curve stays consistent from start to finish,
that would be a weightless curve.
You can have the curve be increasingly strong at the start
or the end of the line
to give it weight in a specific direction.
This is very, very important to practise
because we spend our entire childhoods writing
letters and shapes which curve in a very balanced way,
but the more you can break away from that
the more organic your drawings will be,
so warm up with these often.
Alright, let's get into those simplifications and reductions.
Or, rather maybe mention another little side thing...?
Sorry, there's a lot of ways to think about arms.
Such as the chain,
a common trick for approaching arms
is to imagine a giant linking chain -
the idea being that since the upper arm is
wider from the side view than from a front view,
and meanwhile the forearm is the opposite,
it will generally create a nice little back and forth between wide and narrow
which is definitely good for aesthetic purposes.
So you can use that as a little mental note when applicable.
Meanwhile, to go back to what we've just talked about
with curve weight, the most important mental note I fixate on
is usually just where to weight the curve for each part of the arm.
On the bicep side of the upper arm,
the curve weight is further toward the elbow.
Whereas on the back or tricep side of things,
the curve weight is closer to the shoulder.
The brachioradialis is definitely weighted toward the upper forearm,
but is more rounded and gradual than
the opposite side of the forearm.
All of these things relate to
the actual muscle bodies of each muscle group,
the tricep being the most important one
to always remember, because
the muscle bodies are located in the top half of the upper arm.
Okay so let's sum up the straight arm simplifications
a bit more directly.
Back view of the arm, pop forward, minimal twisting.
The upper arm might as well just be a simple cylinder
with minimal tapering.
But the lower arm is going to feel
closer to an upside down bowling pin.
The important part is that
the exterior side, with the brachioradialis
is going to not only curve outward more than the interior side,
but also come up a bit higher than it.
It should definitely feel like
it starts its s-curve above the elbow.
If we raise the arm up out to the side,
yes you'll get a bit of the chain concept,
but since you'll probably not be drawing massive bodybuilders
it can become pretty minor.
You do want to make sure that
you're thinking about weight and gravity though.
Obviously this gets a lot more extreme with age,
but on any body type
you should still be using these ideas
to give you at least a little bit of subtle curve weight.
Another useful reference point to think about
comes from the shoulder muscle.
The deltoid comes down to a bit
of a point on the exterior of the arm.
While not exact, this can still be used
as a good way to indicate a break
between the front bicep side of the arm,
and the rare tricep side.
Especially when you're dealing with more complex poses
and off angle views.
If I draw a quick arm over here on the left
from a slightly awkward angle,
adding the deltoid and letting it point a line
towards the elbow can at least
help us visualise the tricep and bicep sides of the arm.
If this drawing looks weirdly off to you at first,
that's good!
The brachioradialis was not coming from the correct spot.
Let's first recall that the brachioradialis should come from
under the triceps and over the biceps,
and using that line from the deltoid
we can visualise this insertion
much more clearly.
Moving along,
some of these straight armed elbows
might be looking a bit wonky.
So let's briefly mention them.
The most important part of simplifying the elbow'
will definitely come from seeing
the triceps and humerus all come together in a mass
that leads straight down through the elbow
and into the ulna.
The funny bone and radius both become a bit
indented on a straight arm,
so you'll mostly see these
little pockets of depth off to
both sides of the triceps and ulna, with
the forearm muscles pulling the forms back out
and really solidifying those crevices.
There's definitely a lot of skin going on
in this area, so it tends to become quite
wrinkly. There's even a slang name for this
folded up skin - it's called the wenis.
So, everybody should draw the wenis, the wenis is not a dance,
and I'm happy to tell you this in advance.
[laughs] Anyway, wrinkles are tricky. The general rule is to fold the skin with
c-curves and s-curves in a way that squishes the curves together
without ever feeling like they're going to cross each other
or pass through the extended implied
lines of other curves.
You can compress a bunch of them into
a small space, or just a couple, but I recommend wrinkling things up
a bit above the elbow with perhaps some
more drapery style folds hanging underneath.
You can definitely develop your own stylistic
approach to wrinkles, and they should feel similar in theory to clothing folds,
but more organic with the lines.
Just keep in mind, like with clothing folds,
doing less is usually better when learning.
Alright, a little bit more drawing in this section, because I want to
also just quickly mention some size relations.
I'm a serial offender of making my deltoids too small in drawings,
so I'm trying to correct that. I think it can be useful to think of the upper
arms as a length that goes from the top of the shoulder to the elbow.
The top third of that length can be the
distance of the deltoid going down the arm.
I barely mentioned it before, but the triceps
really have two main visible muscle bodies on the back of the arm.
While they both have those high up muscle bodies,
the interior side one is a bit longer down toward the elbow,
while the exterior one is even more focussed at the top.
The bottom of these muscle bodies and strong separation of them
occurs roughly halfway down the upper arm unit, that we mentioned going
from top of shoulder to elbow.
You can kind of indicate this with a little butt shape on the back of the arm,
especially if it's being flexed. The arm, not the butt.
Okay, moving along to the world of movement,
the elbow is basically just a fancy hinge
joint with the funny bone on the interior, the ulna being the king in the center,
and the radius on the exterior. When the arm is straight, they somewhat
line up with the ulna sticking out a bit.
From the interior view though, once
we start curling the arm, obviously the funny bone isn't going anywhere.
But the ulna is going to hinge around it and form a very boxy and angular
silhouette, by letting your brain fixate on the line from funny bone to ulna.
All of the tissue of the arm is going to crease at the insertion of the bicep and
form a bit of a line that points mostly toward the funny bone side of things.
The important take away is that interior arm equals boxy shape and long crease.
Also, when you raise your arm with your bicep toward the sky,
that means the deltoid is going to be pulled to the back of the shoulder.
As it, once again, needs to be pointing towards the exterior line between
bicep and tricep.
Anyway, the exterior elbow view is a bit interesting.
You'll of course be seeing the deltoid a lot more in this view
where the exterior is facing back,
but the interesting part is that you're now seeing
both the radius and ulna in the straightened arm view.
This means that when you curl your arm, those two lower
arm bones are going to be traveling together.
Even though the silhouette will fundamentally be the same,
I find it very useful to acknowledge this anatomy by making the elbow
feel like it just rounds up to and around these bones,
instead of feeling boxy.
You might also remember that the brachioradialis is on the exterior side,
so that will create a mass in form that will squeeze from upper arm
to lower arm.
Because of this mass, the exterior crease here becomes a lot more
chubbier and compressed.
I like to use a shorter and splitting crease to hint at this
thicker form.
And you should try to hint at these things in any body type.
From a different view, you can get some idea how all of these bones
and muscles are working, but for now let's jump over to the
forearm movements, because we have rotation to deal with.
If you stick your right harm out in front of you,
palm side up, this is the least twisted view of your forearem.
The muscles and bones just carry forth to the hand in a linear fashion.
This represents one extreme of your rotational movement.
As we rotate the hand, the elbow won't be changing much,
but the radius and brachioradialis will start twisting a bit
to line up vertically at the wrist.
The best thing you should observe on your own arm
is how the s-curves are just as you rotate your hand.
I'm not in love with the drawing on the right here,
but the interior ulna side of things definitely changes up its
s-curve the most, whereas the exterior side
just shifts weight a little.
Once your palm is facing downwards, the full range of motion is complete.
This is as far as things can twist.
The radius and ulna are now on opposite sides from the elbow.
You might be thinking, 'what if I want to give a thumbs down?'
Well, physically you can't. So be sure to remember that and like this video.
If you do really want to point your thumb down,
it requires you to actually rotate your entire arm so that your
elbow is facing a different direction.
Lastly, here I'll just mention, when your arms are at rest at your sides,
the default comfortable state is that central, half-twisted state,
not the completely untwisted state.
Alright, let's go back to reducing information and recap what we've learned.
Of course, it's pretty fun to draw giant musclebound arms,
especially when you're trying to commit all these concepts to memory,
but we also want to be able to simplify these things down
into little anime stick arms.
When you start out in art, it's fine to just think of the upper and lower arms
as just cylinders, and as you get more comfortable,
you can introduce some tapering into these forms.
Eventually you will want to be capable of some level
of form complexity. These cross sections are never just round.
They have weird oblong shapes and blobby looking contours.
I like to practice these things with what I would call
skinny muscle forms.
Maybe it's just my Samurai Champloo roots coming through again.
A quick example though, starting with a deltoid and shoulder,
letting it point toward an elbow, think I'll twist the bicep to the bottom on this one,
bicep means curve weight closer to elbows, so we can even dive in
with some angular shapes.
With the bicep facing forward, that means the deltoid
can be a bit further on top instead of on the back,
and we can even hint at some tricep form above the separating line.
That line will let us know where to pull the brachioradialis from,
and then we can decide on the hand rotation and
make everything line up.
Design wise, it's good to play around with the ratios of rounded
shapes and angular shapes.
We alluded earlier to the exterior side feeling more rounded
and the interior feeling more angular, when
discussing the elbow hinge,
so let's just run with that a bit more.
What if we just always simplified things around the elbow
by playing up rounded exteriors and angular interiors in the forearm?
I just noticed that that letter pointing towards the tricep is a D instead of a T.
Clearly getting a bit delirious at this point.
Regardless, let's keep sketching.
Here's a quick side view, still mostly practicing curve weights and that brachioradialis.
Some slightly more exciting things we could try
would be playing around with perspective and dynamic angles.
If we imagine a Spiderman type arm pose, we could still
think about where we could exaggerate our forearm muscles.
I'll be honest though, I sort of got distracted right after starting
this one, because I thought of some more stuff to mention.
Such as, what does it look like if you
just have your elbow sticking up in the air
with your arm curled behind it?
A lot of tricep weight at the bottom,
but it really things out into a very skeletal look
at the elbow. It does give a nice look at the radius, ulna and funny bone.
This becomes instantly obscured by the forearm
once you straighten the arm out a bit with those forearm muscles
just taking over both sides of the elbow.
But, this made me think of another scenario,
how about when you're resting your weight
on your elbow at a desk or table?
Where do those forearm muscles go then?
Well, since the brachioradialis connects to the humerus,
it actually sits up higher, away from the elbow on the exterior side of things.
I guess that's obvious enough, kind of like how it would look if you were
drinking something.
Just always be keeping track of where the thumb is,
and where the exterior and interior of the elbow are,
and you'll be fine.
Now, we always have a common mistakes part in these videos.
But, I think I've gone over things so much that we can try a pop quiz instead.
I'll show a quick drawing with some weird mistake, and we'll see if
you can deduce the problem.
Like this. What's wrong with this?
Well, you have two possible answers on this one, since we can't see the shoulder.
We seem to be looking at the front of an arm, so either the brachioradialis
is on the wrong side, or the hand should be mirrored.
How about this one? Anything seem off to you?
Well, I'm messing with you a bit, because
it's the same thing, except this time you can see the deltoid,
so there's only one answer.
The brachioradialis is on the wrong side again. It should be on the exterior,
not interior.
Alright, I promise this one will be different.
What's wrong this time?
Doesn't seem too far off, the deltoid and forearm stuff seem okayish,
this might be a subtle one, but I reversed the weight on the
bicep and tricep curves.
Remember the tricep should have mass closer to the shoulder, and the bicep
curves closer to the elbow.
That's a bit better.
One last one.
What's wrong now?
Hmm, the brachioradialis is on the exterior, so that's fine.
But it still looks a little strange.
Well, that's because it needs to go over the bicep, not under it.
And with that, I think we're done learning.
You have graduated to the part of the video where we just take everything
we learned and try to draw and paint arms from imagination.
Hopefully they wind up looking alright.
I will be using a simple flat brush for these lines, with pressure sensitivity
mostly on size, but with a bit on opacity.
That should make it feel pretty comfy and natural.
One big concern I had going into this final section,
is trying to make sure it stays focused on arms.
Shoulders are a bit unavoidable, but I tried experimenting
with ways to make the hands get less attention.
Literal disjointed fingers and whatnot.
Unfortunately, that actually made them stand out more,
in rules of focus and contrast and whatnot,
so eventually I'll get rid of that idea.
What actually wound up being the biggest issue
is just trying to come up with a good variety of poses.
Once again, I considered crazy foreshortening,
but then the page might feel less cohesive with the more traditional
perspectives.
I don't know. But I'm definitely enjoying the line art quality.
There are a couple of disjointed lines here and there,
but I tried to hit a good number of the c-curves and s-curves
in single strokes.
That can result in a lot of putting something down and then undoing it,
redoing it, until I figure out what I want it to look like,
but I'm mostly okay with that method.
I can't be too chaotic with styles, but I did try to at least vary up
the muscularity levels a bit as it goes on.
My brain was pretty drained from all the previous arm drawings,
so there are definitely a couple of moments where I've made up an arm
and then moments later realised it was almost identical to one that was
already on the page, like this last one.
But I just decided to adjust the angle of it a bit and move on.
For colors, I don't know how much I can really say that would be new,
the skin video as well as the other videos have really covered the general
stuff. But you can see I've lightened the line art into a lighter reddish tone,
and then threw in my normal dull minty background.
I like to mask out everything in order to watch transparency, which can
be a bit tedious, but usually worth it in the long run.
A big piece of advice is to make sure you don't instinctually start
pressing hard with your stylus when blocking.
This is always the most dangerous time for your hand and wrist health,
because we tend to dig in harder when filling things in.
Pressure is bad for your tendons.
Anyway, once everything is blocked in, we can try out a variety
of skin tones across the page.
This is also a great time to introduce some hue variety by air brushing
in reds on areas that might catch more sun damage, and things like that.
The next step is form rendering, and I know some people like a more
smooth gradiation and some people like a more chunkier chaotic painting approach.
But, I'm going to try out some weirder ideas,
and just try defining forms with blocky, contour tracing strokes.
Honestly it's a bit weird at times for these videos, because I don't find myself
with a strong preference.
In my mind, as long as you have some understanding of the forms
you can always either step up how abstract and chunky things are,
or step it back into hypersoft air brushing.
In any case, the important part is just knowing where the hard edges
and soft edges should be.
Now, how do you know which edges are hard and which are soft?
Well, it's simple. If you would be okay with seeing an actual line at a specific
spot in your drawing, then that can be a hard edge in your painting.
If you think a line would look bad in your drawing, then stick to soft edges there.
I already made pretty much all of the lines I wanted to make in the drawing stage,
so those will be the only hard edges.
Anyway, I started out pretty experimental,
with some of the painting stuff early on,
but I wasn't that into it this time, so I'm slowly going to be dialling that back
as we go. Almost all of these arms
are going to be out of direct light, you know, ambient light for the most part,
aside from the one on the right that is reaching toward us.
Doing this somewhat makes the whole image a bit darker and more saturated than
I wanted, so I'll be desaturating and lightening it a bit as we go.
Other than that, I definitely kept the line art in play for a lot longer than I normally do.
It's not until most of the form rendering is complete that I actually
flatten things down and start painting out the lines.
This is also when I start playing with slightly more interesting shapes
in some of them.
The rim light is going to be pretty subtle today,
I definitely made it more limelight than I normally recommend to people,
but still trying to at least taper those lines and find some
chunkier shapes with it.
To bring back some of the other fun stuff from the skin rendering video,
I decided to put in some body hair on the top left arm.
Just a bit of fun with desaturating colors and pattern-based brushwork.
This was also when I decided to at least connect the fingers that I had there,
but we're almost done, so the last
thing I want to have fun with, is bringing some of that body hair into the rim light.
It makes the rim light a lot more fun.
Definitely recommend trying it when you can.
And, with that, this monster of a video is finally complete.
It has been a journey, and while the drawings and paintings might not be perfect,
hopefully you at least feel a bit more confident
about being able to draw some fun arms from imagination.
As always, the best way to fully learn is to mix in
equal parts of drawing from human reference,
doing master copies of other artists you like,
and drawing from imagination.
No matter how good or bad you might feel about
one of these three parts, do them all evenly regardless.
We only focussed on three main muscles in this video,
so if you find yourself wanting to build up more complexity,
just go check out one of the other amazing art YouTube
channels that dives a bit deeper.
Alright, I want to thank you all so much
or at least giving this video a chance,
I'm not a frequent uploader, so be sure to subecribe
if you don't want to miss out on the
handful of videos I put out each year.
Of course, if you want some fun, specialised content
the brainstorm classes have been going really well
and its definitely worth your time and money
if you haven't tried them out yet.
Info is down in the description.
I also, of course, do want to give an earnest thank you
to the Patreon supporters that chip in
money to keep these videos coming.
You guys are wondeful.
Seeya everyone.
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