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 pinkie 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
focused 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 arm out 
in front of you, palm side up,

this is the least twisted 
view of your forearm.

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 adjust 
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 thins 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 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, just 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 focused 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
for at least giving this video a chance,

I'm not a frequent uploader, 
so be sure to subscribe 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.

Cya everyone.