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Embrace by gsendr1

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Inktober 30 Fire Rush by ScottaHemi
Terrier Daki Animated by Shishiworks
Terrier Animation 2023 by Shishiworks
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Anthro, Nonhuman
It's the Great Naga, Charlie Brown! by DarkwingDork1
Changing Rooptials by DarkwingDork1
adopt batch 211: monster manual mommies closed! by slushiipanda
Arm yourself! by DarkwingDork1
Anthro, Nonhuman
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Extra arms: anatomy studyRecently, I've been playing with 3D models of bones. Here I want to explore three possible configurations for the bones of a human body with 4 arms (+ a bonus with 6 arms at the end). Each configuration has its own description, discussing the advantages/disadvantages in terms of functionality/mobility and aesthetics.Of course, there are many alternative ways the extra arms could be implemented. In my case, I begin with the normal human skeleton as a base and I try to see how the extra arms could be integrated with as few changes as possible to the skeleton, because I want them to resemble more to normal humans. For example, I want to avoid stuff like an elongated torso to accommodate the new arms, or extra clavicles to support arms, etc...In my configurations, I focus all the changes on the scapula (the flat shoulder bone), which is enough to accommodate the extra arms. I consider only the bones though, without accounting for the muscles (discussed briefly at the end), ligaments, blood vessels or nerves.By the way, since the skeletons are a bit shy, I don't display their lower parts.,The scapula of a 2-armed human (for reference).The 3 configurations are:1. Extra arms fixed behind the normal arms.2. Extra arms fixed below the normal arms. 3. Extra arms floating below the normal arms. The 6-armed version is a combinations of extra fixed behind the normal arms and extra arms floating below the normal arms. I assume that the extra arms are identical to the original arms adjacent to them. So their movement is basically the same i.e. they mostly extend toward the front of the body., 1. Extra arms fixed behind the normal armsIn this configuration, the extra shoulder articulation is fixed at the same height as the regular arm, directly behind it. The scapula is modified to add the extra arm slot right behind the normal arm:,The scapula of a 4-armed human showing 2 humeri side by side.,The scapula without the humeri to see their sockets.Functionality and mobility:The main advantage of this configuration is when the arms hang downward (typically, at rest when the arms are positioned alongside the body). In such cases, the arms do not collide at all, they are comfortably sitting next to each other. The issue here is when the arms are are extended forward (e.g. hug). In these situations, the range of motion of the back arms is a bit reduced. To enable the back arms to extend forward, the shoulders must be in a forward position (scapulae rotated toward the front), otherwise they would collide with the front arms. Still, their range of motion remains more limited compared to the front arms. For example, the elbows of the back arms cannot touch each other.,(Click to see the animation)Demonstration of some movements in this configuration.When all the arms are directed forward, the back arms cannot get closer from each other since they are blocked by the base of the front arms.,(Click to see the animation) Same animation viewed from another angle. See how the arms align perfectly in parallel when they are at rest. Also, see how the front arms impede the forward movement of the back arms.To improve the mobility of the back arms, especially to reach forward, I see two options (not illustrated here):the base of the back arms could be positioned more outward, and/or the base of the front arms could be positioned more inward i.e. the back shoulders should be wider than the front shoulders, so that the back arms have plenty of space to extend forward.the back arms could be designed to float, i.e. they should have their own extra scapula and/or clavicle to move their bases independently from the front arms. It would enable lowering (resp. elevating) the front arms and elevating (resp. lowering) the back arms, such that the back arms have some room to reach the front.Aesthetics:,Front, top and back views.In terms of appearance, when the arms are properly aligned, it looks like a normal person from the front or from the back. When the arms are not aligned, we don't really see that the arms are actually connected to the body. I like to clearly see the connection at the base of the arms. For all we know, someone could be hidden behind, pretending to add two arms to a normal person in front.Viewed from the side and the top however, the extra arms appear clearly., 2 - Extra arms fixed below the normal arms.I've put the arm socket not precisely directly below the normal arm, but a bit backward and inward, such that it naturally follows the shape of the scapula. This design also helps a bit when the arms are hanging downward so they don't collide as much as if they were perfectly aligned vertically.,The scapula of a 4-armed human showing 2 humeri, one above the other.,The scapula without the humeri to see their sockets.Functionality and mobility:This configuration is essentially the opposite of the previous one, it provides the best range of motion when the arms are extended forward, but the lower arms disturb the upper arms when they are at rest/downward.,(Click to see the animation)Demonstration of some movements in this configuration. All the arms have the same mobility in forward extension. The lower arms are a bit blocked by the base of the upper arms when they are all raised.,(Click to see the animation)Same animation from the other viewpoint. The arms encounter some friction when they are alongside the body. To improve the comfort of the arms, especially when they are hanging downward, I see two options like before:the base of the upper arms could be more outward and/or the base of the lower arms could be more inward i.e. the upper shoulders should be wider than the lower shoulders so that the upper arms have plenty of room at rest (not illustrated here).the lower arms could be floating, i.e. they should have their own extra scapula and/or clavicle to move their bases independently from the upper arms. This way the lower arms can be positioned forward or backward to leave some space to the upper arms. The configuration 3 is a possible implementation of this idea.Aesthetics:,Front, top and back views.When I think about a 4-armed human, this is the first image I have in mind. I like this visually, because it showcases both the upper and lower arms in most of the poses.Note on the view from the top that the lower arms are slightly backward compared to the upper arms.One thing that looks a bit strange is the difference in heights between the lower and upper hands when the arms hang downward., 3 - Extra arms floating below the normal arms.In this configuration I have added an extra bone (codenamed "little scapula") that articulates with the scapula. It offers an extra degree of freedom to the lower arms, which improves the overall comfort and mobility. An extra arm can be right under an upper arm, but when needed, the extra arm can move forward (or backward) to leave some space for the upper arm.It's not represented in the following, but I imagine that there are new muscles to move the new bone.,The scapula of a 4-armed human showing one humerus fixed on the scapula and one humerus floating. This scapula is slightly different from that of a 2-armed human because of the small indentation that has been created to articulate the new bone that is connected to the extra humerus.,The scapula and the new bone without the humeri to see their sockets.Functionality and mobility:This configuration has the advantages of the previous configuration with the extra arms fixed below the upper arms, but mitigates its potential discomfort from arms resting in a hanging position.Because the extra arms are floating, they are weaker than the fixed arms. An idea would be to add two extra clavicles (collarbones) or equivalent bones, to bridge the torso with the extra arms. But I think it would be too apparent under the skin, so it might look too weird.,(Click to see the animation)Demonstration of some movements in this configuration.,(Click to see the animation)Same animation from another viewpoint.Note the passage of the lower arms under the upper arms.The lower arms can remain in front or behind the upper arms. It's less comfortable when they are behind though.,(Click to see the animation) Animation of swapping the position of the lower arms.Aesthetics:,Front, top and back views.Since the new bone between the scapula and the extra arm stick to the rib cage in the upper armpit, they would be mostly invisible under the skin.I like this design because it resembles the configuration 2. However here, I think that the arms are a bit too low. The gap between the two arms is a bit too large. Fortunately, it can be fixed by making the new bone slightly shorter.Also note on the view from the top that the bases of the upper and lower arms are perfectly on top of each other., Final thoughts:Apart from the arms, the rest of these 4-armed skeletons is similar to the regular 2-armed skeleton, so there are not many points of insertion available for the extra shoulders muscles. But there is a way to solve this. In general each of the individual 4 arms are weaker than the individual arms of a 2-armed body. But when they are combined, the 2 arms on one side together have a similar strength as a regular arm. It's quite rare to have to use the full strength of one's arm, but it would often be useful to split that strength in several arms for multitasking. So if the overall strength of a 4-armed body is equivalent to the strength of a regular 2-armed body, there should be the same total volume of muscles in both cases. So based on that reasoning there may be a way to fit everything in. For example, by dividing a normal muscle in two, detaching one half from the normal arm, and attaching it to the extra arm instead. This is illustrated by the following images.,Comparison of the muscles on the normal scapula and a possible implementation of their analogue on the configuration 2. There are 3 muscles represented here: infraspinatus, teres minor and teres major. They are duplicated in smaller versions in the 4-armed body. Each arm has less muscle volume individually compared to a normal arm, but once they are combined by pair, they have basically the same amount of muscle.Also, the arms of a 2-armed body are naturally optimized by evolution in term of position, strength, etc. Therefore, in a 4-armed body, I think it is fine if their counterparts are dominant arms and the extra arms are slightly weaker. In general, I also think the 4 arms could be a bit more slender than the arms of a 2-armed body., Bonus : 6 armsI think that the configuration with extra floating arms combines easily with the configuration that has fixed front and back arms, for a total of 6 arms.,Front, top and back views of the 6-armed skeleton.Visually, viewed from the front or the back, I think it's not that great that a gap appears between the lower and middle arms, but not between the middle and upper arms. Surely, there are other configurations for 6 arms that look better, more symmetrical.Here are some close-up shots of the scapula...,The scapula of a 6-armed human showing 2 humeri fixed on the scapula and one humerus floating.,The scapula and the new bone without the humeri to see their sockets.,Close up of the 6 arms hanging downward.And the animation...,(Click to see the animation)Demonstration of some movements of the 6-armed skeleton., Now, the 2-armed skeleton is sad, it thinks that it's so unfair that the others have extra arms...,The boring skeleton (for reference).
Discount Comm Sheet by Dizzy-Possum
| Commission Price List | by Dizzy-Possum
30 HUMAN POSE REFERENCES - PACK 17 by ERA-7
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Lotr by TRADT-PRODUCTION
April-May by Gulliver63
Jynsadd serious pose by TRADT-PRODUCTION
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Group Info

A club dedicated to artwork of characters with multiple arms.
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Founded 13 Years ago
Jul 1, 2010

Location
Global

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248 Members
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Welcome, Korhann!!

:icongreteh:

Hello everyone!!
After a bit of time, we have a new lead in our group ♥

Congrats to :icondizzy-possum: ! They will be taking care of things from here on out


I want to apologize to everyone for having to leave after doing so little for the group. I promised a lot of things and changes for the group and simply didnt deliver, and I'm sorry for that.


However I trust Korhann to help pick things up, and revive good ol ArmsArmy!!



Thank you everyone for such a great group ♥ ♥ ♥



:icongreteh:
1 Comment
Welcome, Korhann!! December 4, 2018 1 Comment No Favourites
More Journal Entries

Arms Army rules!

Hello and welcome to the Arms Army! :salute:
We specialize in characters with multiple arms.

Submitting work
Click "Contribute art" at the top and choose some work. You can submit one piece per day. The artwork must clearly show a multi-armed subject. Only content not marked mature is accepted.

Human or nonhuman?
Consider only the multiarmed subject(s) in the picture. If the subject looks mostly human, it belongs in human. Otherwise, nonhuman. Most anthro art, and otherwise, are nonhuman. Look in the folders for examples. These are just guidelines as the line is hard to draw sometimes. In such cases, you are free to decide where it belongs.

Becoming a member
Just click "join our group" and you will be a member automatically. Members can submit 5 artworks per day.

Features
Four features are chosen at the start of each month by our curators. Be sure to view them and their artists and send some attention their way. Many are open for requests/trades/commissions, and their userpages will have the most recent information.

:squee: Enjoy!

Admins

Founder


:iconhexaditidom:

Co-Founders


:icondizzy-possum::iconrockmr:

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:iconanthroaliencreatures::iconmultiarmedandrobotic::iconstrange-fascinations::iconfor-the-shokan::icondemon-vamp-monster::iconmultifurry::iconb-and-b-is-awesome::iconmonstersuniversityfc::iconthe-wanderingstar::iconmutant-ua::iconcreatures-plus-extra::iconmachop-family-group::iconbizarreanthros::icondaddylonglegs-comic::iconbug-anthros:

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:icondragonus18:
Dragonus18 Featured By Owner Jul 11, 2023
I'm happy to he a part of this group. I hope you all love Veronica and the arms she brings to this page. 😀
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:icondravencleary:
Dravencleary Featured By Owner May 10, 2020
HI i dont check Da much these days but I saw there was a (now expired) Request for one of my pics. Id be happy to accept it if its sent again
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:icondizzy-possum:
Dizzy-Possum Featured By Owner May 11, 2020  Hobbyist General Artist
can send again
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:iconvarkarrus:
varkarrus Featured By Owner Jun 20, 2018  Hobbyist Digital Artist
Do you think there could be a more clear distinction between whether you use the human gallery vs the anthro/non-human one?

I think like, humanoid characters, including human-like monsters, should go into the former. Then, the other one should pretty much be anthro characters, and mostly non-humanoid ones (like monstrous body horror)
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:icongreteh:
Greteh Featured By Owner Jun 20, 2018  Hobbyist Digital Artist
I think in most cases it varies on what the submitter thinks, whether or not they believe its more human or anthro.

(That's something I plan on sort of fixing up as well, giving more categories to help with all ranges)
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:iconazabachesilver:
AzabacheSilver Featured By Owner May 29, 2018  Hobbyist General Artist
Should have submitted this one first
(ALT SW) Quadrachion Empire, Quadrachion Infantry by TinkerTanker44432
The Quadrachion, alien race of four armed soldiers
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:icontinkertanker44432:
TinkerTanker44432 Featured By Owner May 29, 2018  Hobbyist Digital Artist
Excuse me?
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:iconazabachesilver:
AzabacheSilver Featured By Owner May 29, 2018  Hobbyist General Artist
Sorry, this a group that features characters with more than two arms. I guess I misunderstood your character concept here. I was just submitting it here so your work would get more exposure 😥
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:icontinkertanker44432:
TinkerTanker44432 Featured By Owner May 29, 2018  Hobbyist Digital Artist
I fully understand and my character does indeed have more than two arms. I was simply caught off guard. Sorry for the brash response.
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(1 Reply)
:icondaniechidna:
DaniEchidna Featured By Owner Apr 5, 2018  Hobbyist General Artist
Thank you for featuring my work!
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