No matter if you are drawing an action comic or a dramatic mystery with lots of dialogue, characters’ arms will be likely front and center in many panels. Camera angles tend to focus on characters’ faces and upper bodies which include the arms.
Not only that but people tend to speak with their hands. Adding expressive body language with dynamic arms is a must-have to keep any reader engaged and entertained.
Even if you haven’t previously realized what I just explained, I think people inherently know how important arm anatomy is when compared to all the anatomy that could be studied. In my opinion, they rank 3rd in importance; After learning heads and hands.
Arm anatomy may seem like it’s easier to wrap your head around, but that’s only because they are in our vision pretty much non-stop since the day we are born.
In actuality, because of their cylindrical nature and how the forearm can rotate, the task of fully mapping out the musculature can be a cumbersome one. But don’t fret, I’m going distil everything I know in any easy to understand way.
Let’s get into it!
Arm Proportions
The first thing to understand about the arm, as a structure, is its relative proportion to the rest of the body. First to note is that the arm can be divided in half at the elbow. That length is good to remember because it also happens to be the height of the rib cage.
Keeping this length consistently uniform is an easy way to know that your anatomy is built on an accurate and proportionate structure.
Where To Start
As with all figure drawing, a great place to begin is with a gesture. A there’s a lot that can be described with a gesture sketch and I’ll point them out has I discuss thee three examples below.
First, on the left is the simplest gesture of the arm which is represented by two linked ‘C’ curves. There are two things to point out here. See how the two strokes curve in the same direction? That is because both the upper and lower arm have a bend that stays uniform.
This constant is a good landmark for starting your drawings. Next, pay attention to the lengths of each curve. They are more or less the same and if we drew the rib cage next to this it would also have that same length.
Once you put a couple of marks down for your arm placement, it may be a good idea to give it volume. The simplest volume we can use for the arm is a cylinder.
Make sure to keep them about the same length and always draw through to ensure the volume is accurate and can be easily understood even in this primitive form. The last example is of the volume but rendered as well.
Putting a little bit of shadow goes a long way to make shapes and volumes ‘pop’. This extra level of rendering is especially useful if you are also trying to create a composition at the same time.
(Most times this will be the case since we are story artists and should be always framing our figures for creating the most dynamic shots… even when practicing).
Using Perspective
Because the arm is not perfectly round, we must modify the arm volume to something more reflective of the actual anatomy. To do this you must, first, mould the cylinder in to more of a rectangular cube with rounded corners. Take a look at the upper arm in this example.
Converting the volume in to this more angular form also will start to show the arm in a more accurate perspective. As you will see later, the lower arm can twist and rotate relative to the upper arm. And we need perspective to show direction of each section of the arm.
Last, I’ve taken the molding to an additional level and added some meat to the lower arm. By adding this extra mass, you will now be able to tell where the forearm is rounded and where it is angular; at the wrist.
Orientation
Before we get into breaking the arm anatomy down to specific groups, let’s take a look at an overview of how the arm links together. There is a natural flow to the layering of the muscles and its really cool to study.
In this example, I’ve drawn the arm in perspective where the wrist is closest to the viewer. In each of these exaggerations, you will start to see more and more how the muscles layer on top of each other.
The easiest way to explain it is to relate it to a chain.
Just how links in a chain rotate in order to connect to one another, so does the muscles in the arm. The deltoid and the forearm face one direction while the bicep and triceps face in another direction.
When sketching in your muscles, keep this in mind. All over the human body is this example of ‘Active’ layering. If done correctly it will create its own type of dynamics even in a default pose.
Anatomy Breakdown
As we did before, let’s start with the bones of the arm. I’m not really concerned with specific names of the muscles and bones, but I do admit that knowing them helps to organize the knowledge.
The things you need to know from the bone structure is that the upper arm bone (humerus) and the lower set (radius and ulna) both can rotate. The lower has much more range of motion but that gets complex pretty quickly.
For now, I’ve drawn the front and back view of the arm and will now layer on the musculature.
I’ve color coded each muscle group to make it easier to recognize how they wrap around the bones. Take note how each muscle group tapers past one anther to create a cross weave like pattern.
This is important: All muscles have a beginning and an end, so make sure to visualize where the beginning and ending is in 3D space.
It will actually help immensely to have a 3D model handy (digital or physical) as you learn these muscle groups. You will be able to rotate the model and solidify in your mind where the start and end points are.
Lastly, I want to mention that I have grouped these muscles in a way that works for me and many more educated teachers. (specifically Michael Hampton).
Before I break down the muscle groups, I also wanted to point out that I will be layering on the muscles in a pronated (or palm down) orientation. This is also a great time to mention that the lower arm can rotate just about 180 degrees.
This breakdown is right around that 180 degree mark.
Let’s do this!
Deltoid
At the the top of the arm is the deltoid, the main muscle of the shoulder. The deltoid has three big egg like shapes that wrap around the bone. In actuality, the deltoid is not egg like at all.
The muscle begins from the chest and shoulder blade respectively and ends on the upper arm bone.
Bicep
Alright! On to the star of all the muscles; the bicep. The shape is pretty simple and spans the length of the upper arm bone. The bicep should be an easy landmark to wrap the other muscles.
The bicep faces forward when the arm is in the open and faces toward the chest when the arm is rotated palm down.
Triceps
The biggest mass of the upper arm is the triceps. It is most notable on the back of the arm and is made up of two big groups. Each group wraps around to the inner and outer side of the arm.
The upper part tucks under the deltoid and the lower portion splits and wedges around the Ridge Muscles and the Flexors respectively.
Brachialis
This “filler muscle” supports the other main muscle groups of the upper arm. This one tucks right in between everything. On the upper portion its in between the triceps and the biceps, directly under the deltoid.
It wedges in the lower half right next to the Ridge Muscle group. Adding this muscle group will do wonders for your upper arm anatomy because its a muscle we all recognize when its placed well. No doubt it will make your anatomy look natural and real.
Pronator
This one muscle is responsible for flipping the lower arm. This is the wrapping muscle that shapes the inside portion of the ‘inner elbow’. It wraps from the under portion of the triceps to layer on top of the biceps.
Great that covers the upper arm! The lower arm is a bit more complex because the tendons split and connect to the hand, fingers and wrist. However, I’ll be presenting the groups in the simplest way that I know.
Ridge Muscles
I like to think of the ridge muscles as the great bridge. It wraps from mid way on the upper arm bone all the way down to the thumb side of the lower bone. If you tilt your hand up and flex, those are the ridge muscles!
I think they are my favorite grouping because it creates such a cool silhouette and it appears prominent in most people.
Flexors
The flexors are easy to remember because its the forearm muscle group that bulges when you do the classic flex by tilting your hand toward you. This group is also pretty easy to memorize because of how condensed it is.
Extensors
And lastly, the unsung heroes, the extensor muscle group. These are the muscles on top / back side of the lower arm. They extend down to the fingers and naturally are used when the fingers need to move.
They are the most intricate of the forearm and probably the most ‘ad libbed’ when artist's do their work. When these muscle are developed they created a lot of ridges and valley that will show in dramatic lighting. Any action comic will be featuring these front and center!
Excellent. I know that was a lot of info but hopefully that the words in tandem with the art it will stick and it will lead you down a road of curiosity.
Learning From the Pros
Before we get drawing let’s look at a few examples from master comic book artists.
Lesson 1: This one can be learned by looking to almost every comic artist out there. It is always better to hint at the muscle by only drawing the shadows of the most prominent muscle groups.
Lesson 2: In some styles this is very apparent but it is a great idea to exaggerate the straightness of the bone in the arm when it is visible.
Lesson 3: Always, always draw female arms less defined. Even the most muscular women tend to have more fat than their male counterparts.
Lesson 4: Knowing the beginning and ending of each muscle group is a great tool when it comes to posing. When the arm bends it will become apparent that the muscle will bulge a bit but still stay in position.
Lesson 5: When shading, consider each muscle group as a simple shape. This will allow you to see past the complexities and only focus on the fundamentals of lighting.
Now let’s get to drawing!
I’m going to walk you through drawing an arm, step by step.
Step 1: Draw The Arm Gesture
Start with the gesture of the arm. It should look like two sweeping ‘c’ curves. Remember to keep the concavity uniform between the two.
Step 2: Draw The Base Forms of The Arm
Draw in simple cylinders to represent the upper and lower arms. Use foreshortening to show their position in 3D space. Also, make sure to draw-through.
Step 3: Rough In The Arm Muscles
Great! Now rough in the musculature by using ovals and football shapes to block in their relative position.
Step 4: Clean Up The Arm Drawing
Erase away the under drawing and then use it to make clean contour lines. Make sure to use line weights and wedging to make foreshortening look believable.
Step 5: Block In The Shadows
It’s time to add shadows! Block in the mass of shadows to best show the volume. Remember the basic cylinder example and try to simplify the lighting in your mind.
Step 6: Define Perspective For Costuming
Now to bring some interest to the pose, let’s add a costume. We will first add a vanishing point and a one point perspective grid.
Step 7: Add Armor Elements
Use the perspective grid to add these aggressive blades. Also add a gauntlet seam to mark the end of the armor.
Step 8: White Out The Blades
Here’s the first step where we will add white. So if you are using ink, grab some white out and erase the lines within the blades. This will pop them to the top and make it look like that they’re perpendicular to the forearm muscles.
Step 9: Add Fabric Wrinkles
To make this gauntlet look more attached to the arm let’s add some wrinkles in the fabric. Follow the contour of the arm to make sure it looks believable. I’ve also added cast shadow under the blades.
Step 10: Wrinkle Highlights
Here’s the second white out phase. Use an eraser or white out to wipe away the lines and shadow adjacent to the wrinkle lines. This will really bring realism and show the specularity of the armor.
Step 11: Draw In Render Lines
Lastly, let’s bring some polish by adding render lines to the massing of shadows. Excellent. You’ve successfully made a great looking arm!
Before You Go
If you made it this far and tried out the exercise, I hope it’s intrigued you to continue studying the anatomy of the arm. It is a rather dense and wrapping set of muscle groups so don’t be ashamed if you don’t have all the positioning locked down. (I know that I don’t).
It takes consistent effort and even then a whole lot of mileage of drawing, making mistakes and drawing some more.
I’m stoked to be writing all these tutorials for HTDC and I encourage you to check out all of the other great, free ones here on the site!
There is a growing community at howtodrawcomics.net and all their social media pages so get in there and ask for feedback on your work. Feedback is key to learning.
For some of you who are ambitious, I would also recommend checking out the Mentorship program as well for more honed progress with a pro. If you have any questions regarding this lesson, please leave a comment or DM me on Twitter or Instagram @catapanoart.
And, lastly, if you like my work, I have a successfully crowdfunded comic book called STAR CIRCUIT. If you like sci-fi and cyberpunk you can learn more about it at joecatapanoart.com.
Thank you for reading.
-Joe Catapano
Tutorial by Joe Catapano
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