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 dont 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 wont be the funniest video in this series or anything
but it will be definitely be the most humourous
so roll up your sleeves and lets get to work
starting out with structure
weve alreday covered both shoulders and hands
in other videos
so we just need to make sure we can bridge these things together
im sketching a quick front side and back few of the shoulders to start
seeing a shoulder and torso without the arm
always reminds me of a little lamb or something
but anyway were 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 arent 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 orginates
from the exterior side of the elbow
aka the side thats 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 extention of the humerus
which protrudes from the inner side of the elbow
closest to the thigh
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 friends' funny bone with your pencil or stylus
its, you know, free comedy
alright i added some hands to these drawings
and i know this isnt the hands video
but since wrists and organic offsets are so important
lets do a quick recap at that connection anyway
now keep in mind by the time
the radius and ulna get to the wrist
theyll 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 youre 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 im making
hopefully that seems easy enough
lets get back to structure and talk about the muscle side of things
were 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 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 back of the ulna
and yes the deltoids of course the shoulder muscles
but the third muscle that were going to be fixated 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
were going all in on the bre-bre (brachioradialis)
i think thats enough structure so
lets 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
dont 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 its good to practice that level of control
but an even more important thing to practise
is your ability to weight your cuves
weighting your curves means changing of
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 and 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 lets get into those simplifications and reductions
or rather maybe mention another little side thing
sorry theres 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 the 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 weve 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 its 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 lets sum up the straight arm simplications
a bit more directly
back view of the arm pop forward minimal twisting
the upper arm might as well 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 of 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 youll get a bit of the chain concept
but since youll probably not be drawing massive bodybuilders
it can become pretty minor
you do want to make sure that
youre thinking of 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 youre 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 a deltoid and letting it point a line
towards the elbow can at least
help us visualise the tricep and bicep sides of the arm
this drawing looks weirdly off to you at first
thats good
the brachioradialis was not coming from the correct spot
lets 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 arms and elbows
might be looking a bit wonky
so lets briefly mention them
the most important part of simple "find 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 youll mostly see these
pockets of depth off to
both sides of the triceps and ulna
the forearm muscles pulling the forms back out
and really solidifying those crevices