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How to Draw the Rib Cage – Human Anatomy for Artists

How to Draw the Rib Cage – Human Anatomy for Artists


In the last episode we learned the anatomy
of the rib cage. If you haven’t seen that one yet, make sure you don’t miss it. In this episode, I’ll show you how to draw
the forms of the rib cage step by step. I always like to start my drawings with the
biggest shapes first. In this case it will be the egg-like shape. It’s thinner at the
top where the neck attaches, and thickest about ⅓ from the bottom. Try not to draw
the entire shape with one stroke. Construct the shape with many segments, analyzing the
angle of each line as you go. Constructing a shape from many angles like this allows
you to visualize the shape and spend more time making sure it’s the correct shape.
Rather than doing it in one stroke hoping your hand lands in the right spot. You can see how with this shape I established
the angle of the top plane, front plane, the angle between the corners of the rib cage,
and the curve of the bottom and back. I’m being specific about each section of the shape
while maintaining the tilt and the width to height relationship of the overall shape. The top plane of the rib cage tilts forward,
so keep that in mind as you try to visualize the planes. Find the bottom of the sternum. Remember,
it’s about half way between the pit of the neck and the bottom of the rib cage. The cartilage that defines the thoracic arch
starts from the bottom of the sternum. So, from there I’ll extend the thoracic arch
shape, while considering the way perspective would affect that shape. I like to relate one side to the other and
make sure that the angle of that line follows the angle of the front plane as if this was
a box. I’ll do a simplified version of the rib cage after this to show you what I mean. This side of the bottom plane is covered up,
but I’ll ghost it in anyway so I can visualize these forms better. Indicate the edges of the sternum, curving
over the front plane. A little notch in here for the xiphoid process And we need an indication for the edge between
the front plane and side plane. This is like the edge on the box. Everything on the front or back plane will
be at this angle, like a box in perspective. Let me show you what I mean when I talk about
the rib cage being a box. We’ll think of the front of the rib cage
as this flat plane that’s rotated slightly to the left and downward. The widest part of the rib cage is ⅓ from
the bottom, so from there I’ll extend a plane inward. Still part of the front plane
just getting narrower. From that, we can complete the box with a
side plane and top plane. So, we have the big simplified volume of the
rib cage, and we can just draw the shape of the thoracic arch right on it. Start by finding
the bottom of the sternum and then some major angles downward toward the corners. And since the thoracic arch is an opening,
we can see the bottom edge on the far side. It will be parallel to the other bottom edge. Let’s clean up this back side. Ok, so that’s the front of the rib cage.
The major structure from the back is very similar, but the wedge shape at the spine
is a bit tricky, so I want to show you how to do that. Start the major shape in the same way I do
for the front. Constructing that shape in parts. For this bottom edge of the back plane, I’m
observing the angle here on his back and trying to imagine what it would look like of it was
a box. And then it transitions to the angle of the side plane. Find the edge between the side plane and back
plane. At this point it should look like a simple 3 dimensional form. Notice that even
though he is leaning back and toward us a bit, we’re not seeing the top plane of the
rib cage. That’s because the top plane tilts forward, so in most back poses the top plane
will be hidden behind the back plane. The 12th rib actually connects to the spine
up here and then angles downward. So, I like to define that edge. It’s the same edge
that we ghosted in from the front view in the previous drawing. It’s a continuation
of the thoracic arch as it curves around the bottom corner of the ribcage and comes back
up to connect to the spine. Ok, this is the part that I wanted to go over.
Remember in the previous video I mentioned that the back plane has a concave wedge that
holds the spine. To cut this wedge shape out, we can think of 3 planes. One center plane,
and 2 side planes. The center plane just follows the curvature of the thoracic vertebrae. I want to point out that this S curve is highly
exaggerated by the trapezius muscles. The spine will curve a little bit, but the curve
we’re seeing here is the muscle pushing in past the center line. Thoracic spine rotation does affect the rib
cage, but not nearly as much as this pose might suggest. Ok, let’s get back to that
wedge. On each side of this center plane, we’ll
have a inward facing side plane. This might just look like 4 vertical lines
to you, but try to imagine the cross contour of this surface. This plane angles like this.
And this plane angles like this. This is part of the back plane. And this is also part of
the back plane. If a trail of ants marched across this surface,
that ant trail would be the cross contour line. Around the side plane, across the back
plane, down the wall of the wedge, across the center, then back up the other wall of
the wedge, and across the rest of the back plane. Keep practicing drawing the forms until you
have them memorized. If you’re struggling with perspective, go back and rewatch my video
on structure. Practice drawing boxes in perspective. Once you can easily draw a box, then you can
start making that box more complicated by cutting out wedges. I hope you guys enjoyed this lesson! If you
want to see more drawing examples go to proko.com/anatomy. I have 8 more examples, which serve as the
answers to the assignment from the last lesson. You’ll also find 3d models of the rib cage
and the simplified rib cage, that you can rotate and draw from any angle. proko.com/anatomy If you’d like to win a free membership to
the premium anatomy course, go to facebook.com/prokotv and share the post for this video. I’ll
choose a random winner next Friday. Good luck! If you like this video, share it with your
friends, and if you want to be updated about new videos click here to subscribe to the
Proko newsletter. Buh Bye!

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44 thoughts on “How to Draw the Rib Cage – Human Anatomy for Artists

  1. This videos just make me want to grab a pencil right now, the medic gave me a prescription and means more proko.

  2. In the premium version, do you show how much the model's spine actually rotates, in the image where the trapezius exaggerates the curve?

  3. Hey Stan, do you think that you'll ever have something on how to draw kids?

    I realize that a lot of the anatomy from your videos would still apply, but I'm just curious about what you feel is important in that area that's different from drawing adults.

    Still loving the anatomy videos, though. They've been helping a ton.

  4. i thought the picture you had was of a dude and u censored it as a joke, but i think its an older woman. pls answer im so confused

  5. Thanks, Proko.
    I'm having a bit of a hard time trying to visualize what's happening when you draw that line that goes from the back of the ribcage to the sternum, at 6:59
    Shouldn't the line follow the bottom contour of the "box", which goes more to the left?

  6. Could you please do another video on heads… a more feminine head cause the drawimgs that are in it look more like superman.

  7. what drawing books you advice us to buy for body studying ?

  8. hello mr.proko. ย I recently found your channel because I was looking for stuff to help me learn how to draw and your videos seem pretty ย helpful. ย Unfortunately ย i barley know how to draw a stick figure so I was wondering what videos I should watch first in order to learn the very basics of drawing

  9. Hello ! I really like your video , gave me great help. I would like to ask your permission to put your video spread to China. Can it?

  10. this can not be all wright ! not . a form for two part , not one for base shape .!?
    one by ones .

  11. I actually had a huge "OHHH!" moment at the end with the "ant trail". I have never understood so easily before. Thank you so much for your videos dude.

  12. This feels so much easier than the pelvis! I still struggle to draw everything right, the spine is not that easy, but it's manageable, but I grew tired of trying to draw pelvises (do you say that?! x), so I moved on, and man, that feels do to draw something that looks right!

  13. i love the ant trail to visualize the cross contour line… makes it easier to imagine for some reason…

  14. i really like your videos mr proko. all of your videos keep being useful even when i avoid using them. they save time from sifting through countless anatomy studies that a lot of the time dont explain as much.

  15. Proko, I admire your artworks, you are a master, my friend. You got a bless from the Gods !

  16. I can not understand something it is very helpless video I hope you are understanding what I say please please please please make other video oh please please my brother please

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