Do a tracing over a model photo of the pectoralis major and all of its bundles. If you’re not sure how to do a tracing, refer back to the “How to do an Anatomy Tracing” lesson.
Invent the pectoralis major on top of photos of Skelly. Use the photos below or if you have the Skelly app, you can create your own pose and draw the pecs on top.

I’ve provided reference photos for part 1 and 2 in the downloads. Download those and start drawing!

Amy Counsell

3mo

this is the finished assignment, some poses were quite difficult to figure out. feedback is much appreciated! <3

Martha Muniz

2mo

Hello! Good work, you're getting the right idea for the pecs. There are a few tweaks that I think can help push your drawings to the next level--mostly using the lines to further indicate the pecs' fanning overlap as it twists and stretches, and more of the thickness of the muscles, especially for a more muscular figure.

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Samuel Sanjaya

3mo

My pec tracing assignment. i tried to draw it on the last picture. Did I do this tracing assignment correctly ? Any feedbacks/critiques will be greatly appreciated

Sita Rabeling

3mo

Repeating anatomy is useful and fun. And I hope to up my drawing skills. I love Stan’s anatomical drawings, clean, precise and simple. I forgot to add: the line on the arm is the bicipital groove on the humerus.

Sita Rabeling

3mo

After watching the critiques I see that the clavicula section would be almost hidden behind the sternal portion. On the right arm.

Karas Rijji

3mo

Here's my assignment

Karas Rijji

3mo

Here are new adjustments to the muscle orientation of the upper pectoralis major muscle.

Sita Rabeling

3mo

Nice!

Manuel Rioja

4mo

Mi assigments ready, uff it was challenging

Jesper Axelsson

4mo

Hi @Manuel Rioja, really nice studies! - In image 5, the lines you've put down for the fibers of the sternal portion bends strangely. I did an attempt of tracing the muscle. If I've understood it right, the sternal portion twists around itself, similar to the twisting of all the pectoralis major portions; the highest portion inserts lowest and vice versa. For the sternal portion: the fibers that attach high at the origin, attach low at the insertion and vice versa. - I assume these are cleaned up drawings, but in your sketches, I would recommend drawing through to make sure that you're aware of where, for example, the abdominal portion is heading for the insertion, if you aren't already doing that. I hope this helps :)

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Ezra

4mo

i wasn’t really sure if i was attaching it to the correct part on the humerus, and had a nit more trouble putting them on skelly when the arms were stretched out.

Gian Amir Calibuso

5mo

@palyo

7mo

Hi everyone! I just finished reviewing these drawings for the pecs assignment after watching the critique and demo videos. I would really appreciate any kind of critique.

Umar Khalimov

6mo

Hey, Palyo. It looks like you are attaching the Sternal section of the muscle a bit too low here, especially in the skelly drawings. From my experience, the clavicular section inserts the lowest on the humerus and the abdominal attaches the highest. The sternal portion's lowest point is either higher than the clavicular's or at least on the same level (sometimes connecting even to the same tendon. There are a ton of genetic variation on this muscle!). That means that Clav. section will overlap every other section and the sternal will overlap the abdominal. In your skelly drawings, abdominal part seems to attach lower than the other two, making the tendon very wide, which wouldn't give enough room for other muscles, like the bicep, to pass through. If you look at dissections of pectoralis major (which I would highly recommend, seeing it on an actual person is extremely useful), the tendon is surprisingly thin for such a big muscle. Good luck!

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@hugpillows

8mo

Just completed the Pecs assignments Did them without the demos first (Left side), then applied what I learned with the demos (Right side). Would appreciate and critiques. Thank you. :)

Jerry Ye

10mo

I just wanna mention, in the assignment image number 5, the model has a tattoo on his arm. I think it's supposed to say 超士 (super human) but instead it says 超土 (slang for super unfashionable).

Samuel Lemons

11mo

Samuel Parker

11mo

Here are my Peccorinos : )

@omambia

11mo

i wanna show you MY PECS!!!!! feedback is very welcome :) (open original to see it in higher quality)

@viny

1yr

done

Tsotne Shonia

1yr

Hi all. Like most, I struggled a lot with understanding the twisting and the arm attachment of the pecs. Looking for more info on it, I found a biomedical research paper from 2019 that was studying variations in the muscle. It has photos of pecs from real, cleaned cadavers, and a lot of photos of the attachment itself from different views. I will post a link to it here. If this causes an issue, I understand if we have to remove it : https://pubmed.ncbi.nlm.nih.gov/31061824/ And yes, according to that research paper, it's a little different from what Stan teaches us in the video. From my understanding : (without looking at the photos, this will make no sense) 1. The attachment has 3 layers of roughly the same length overlapping each other. - The clavicular section occupies an entire layer on its own and is separate from the rest. - The rest occupy the other 2 layers, connected by a U-turn at the most distal part of the attachment. 2. There's no difference between the sternal and abdominal sections at the attachment. The "U" turn is formed roughly at 2/3rds of the sternal section, and this is where all the muscle fibers twist. 3. Because of that U turn design and the fact that the clavicular portion is on a layer of its own : - The top of the sternal portion is at the most medial point of the attachment, and the fibers attach in a more and more distal point, until the 2/3rds split. - That "2/3rds" part of the sternal portion is at the bottom of the attachment, starting to form the turn. - From that point, the rest of the fibers go in the opposite direction, from distal to medial, blending the sternal and abdominal portion as if they were the same thing. - The "last fibers" of the abdominal portion thus attach at the most medial spot too, just next to the "first fibers" of the sternal section. 4. On the photo of the 5th assignment exercise, we can see a huge dimple. I think it is not caused by what Stan explains but by tendons. One of the photos showed a muscle that had a tendonous area right at that spot. Which also explains why it only occurs on some people. Anyways, because I had conflicting information, I was confused as to whether I should follow Stan's instructions, or the information I found on the research paper. I ended up doing a mix of both, and so I got a pretty weird result. I'm not pleased with it, but I was worried I'd be thought of as "wrong" if I weren't following Stan's instructions.

Liandro

1yr

Hey, @Tsotne Shonia! I agree with @Barb R-k, you’ve certainly gone the extra mile in terms of research and analysis for the Pecs studies. By the way, thanks for sharing all the information and your thoughts on this matter! I get your concern that doing the assignment without following exactly what the lesson points out could be thought of being wrong, so your quest for looking deeper into the information makes perfect sense. In my opinion, you managed to work it out pretty well. Overall, I think your drawings look good and the anatomy looks correct. I wonder what is it that you’re not happy with - please feel free to share anything more specific and we can keep discussing. On another note (and this is just a commenting thought), I also find that, when it comes to applying anatomy knowledge in most types of art, it’s less about what is right and mostly about what “looks right”. Not that we shouldn’t care about learning anatomy accurately - by all means, we definitely should. In fact, drawing it in a way that “looks right” demands solid knowledge. It’s just that most artists don’t necessarily need to understand anatomy in the same way biomedical professionals do, since our use of it is so distinct from theirs. Adaptation, simplification, appropriation, idealization or stylization are ingredients that can come into play in an artist’s path, so, a lot of times, believability can be a more relevant criteria to guide some artistic decisions - at least, more so than scientific precision (except maybe for scientific illustrations or alike). In other words, I guess what I mean is: yeah, certainly put in the effort to learn anatomy (or rather anything) in the best way you wish; just try not to overstress, as art is more about communicating solid ideas than about "correctness". Glad to chat! Keep up the good work!

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Barb R-k

1yr

Doing all the extra research shows a lot of dedication and determination to be accurate.

@fefelix

1yr

Hi everyone! In this exercise, I've found it very hard visualizing the overlappings of the pec. maior in a way that shows all muscle directions and insertions while maintaining readability - any solutions for that? Any other feedback and critiques are kindly appreciated as well, of course :)

toni le

1yr

You’re welcome and keep drawing😉

toni le

1yr

hey :) at first nice work! i take the freedom and correct that over your drawing. you connect the pectorals on the humerus on one point and that's can't create the overlapping on this muscle, you can create a fan with stairs. hope that's help...im bad in explaining :D

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Sandra Süsser

1yr

Lesson notes pectoralis major

@mathews

1yr

pecz

@mathews

1yr

yeah I got lazy on these and also I was struggling on the bottom part of the pec, after doing these I checked proko's examples and I got a better idea how it looks like, thanks for the help!

Jesper Axelsson

1yr

Hi @mathews, great work! You seem to know the attachment points well. - It would be nice if you drew through the forms to clarify to the viewer, but mainly yourself, that you know how the muscle is structured and where everything is going. In image #2 for example, it's unclear where the abdominal portion is heading to insert. Hope this helps :)

@unpayedintern123

1yr

Zuzu Soltys

1yr

Hi, I've done the assignment for pecs anatomy lesson. Feedback is kindly appreciated!

@fefelix

1yr

Very clean and easy to read, also all the attachments and general proportions seem correct to me, well done! Two minor critiques: You could achieve more dynamics and energy in your muscle inventions if you showed a bit more relaxation and contraction for each pose. As you can see in the tracings, which you did rather well, the pecs normally don't just hang from the rib cage like a cloth: They bulge out when contracted and stretch thin and straight when relaxed. Furthermore, about your last tracing of Anthony: In this complex pose the directions of the muscle fibres of the sternocostal and abdominal portions are unclear, bc you didn't draw them through where they are being covered by the clavicular portion. It doesn't look like you knew how the muscle forms behave in this section. Also keep an eye out for symmetry: Itn your tracing, it appears that the origin areas for the clavicular portions are not the same on both sides and the abdominal portions seem to vary in size. Here, too, it might be helpful to draw through the forms in order to visualize the exact points where the muscles attach. Then the 3d forms you tried to emphasize around the manubrium, for example, will appear more believable. Hope this helps! Have fun studying. Felix

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Stan Prokopenko

Founder of Proko, artist and teacher of drawing, painting, and anatomy. I try to make my lessons fun and ultra packed with information.