The image about straight woman yaoi (exaggerated hands, slender frames, soft features) vs gay man yaoi (exaggerated chests, stomachs, upper arms, detailed musculature, mature facial features) is really interesting as a sort of "received sensory homunculous". You could also apply it to hentai made by and for straight guys where the girls all have immense breasts. The features that the target audience notices get expanded as if under a microscope, everything else disappears into the background. It's not just desire but also detail, if your audience wants hands you have to put a lot of detail into hands, and that means drawing hands bigger much of the time. If your audience is going to distinguish between hunks and bears you need to draw a lot of shirtless upper body shots and get complex about body composition because someone is going to notice. It's like a visualization of the sexualizing gaze.
I agree, but would like to expand by talking about the trope of "hentai anatomy" and "bad anatomy" more generally. Both through how it expresses sensation, and how it reflects ideas about gender and sexuality.
Honestly I've been of the opinion that "hentai anatomy" isn't so much "inaccurate" as it is an attempt to communicate sensation through a visual medium for a while now. Artists do not draw anatomy and bodily functions inaccurately because they don't understand anatomy or bodily functions, but intentionally for the sake of communicating sensations to their audiance. "Anime Breast Physics" and other examples are not like that because artists haven't seen real boobs, but because they are more preoccupied with trying to convey a sense of what it would feel like to touch them to the audience.
A lot of "bad anatomy" mistakes that people love to point out are in fact not about misunderstanding anatomy insomuch as they are reflections and exaggerations of pre-existing ideas about sex.
I'm going to give an example here, stick with me, I want to lay the groundwork first: Think about the centrality of penetration as a part of sex for straight guys, think about the ideas of strength and dominance associated with the phallus (the gendered and cultural meanings given to and associated with the penis), think about the masculine status attached to the size of the penis, think about the importance of being dominant and how that ties into size and penetration.
In her book "Dude, You're a Fag: Masculinity and Sexuality in High School" Feminist Theorist C.J. Pascoe talks about how she saw teenage boys talk about their (overwhelmingly made up and/or extremely exaggerated) sexual encounters with women. To quote her: “None of these stories were about sexual desire or how attractive the girls were; rather, they were quite gross, about farts, feces, and blood. These stories were about what boys could make girls’ bodies do. That is, the sexual tall tales these boys told when they were together were not so much about indicating sexual desire as about proving their capacity to exercise control on the world around them, primarily through women’s bodies by making them bleed, pass gas, or defecate. These stories also highlighted femininity (much like the fag) as an abject identity. Girls had out-of-control bodies, whereas boys exhibited mastery not only over their own bodies but over girls’ bodies as well. These sorts of girl-getting rituals and storytelling practices constitute “compulsive heterosexuality.” While on the surface they appear to be boys-will-be-boys locker-room talk in which boys objectify girls through bragging about sexual exploits or procuring a kiss, a closer look indicates that they are also about demonstrating the ability to impose a sexualized dominance.” – Page 80
Now, considering all this, does the much beloathed "penetrating the cervix" trope start to make more sense? This is not a defence of the trope (hopefully nobody thought that was the goal here, but if you needed me to tell you that it isn't, I'm glad I did), because it is stupid as fuck, and it does suck. In many places sex education is still really poor, and focused solely on consent and safe sex (which are not bad topics to cover, and they do need to be taught) without any mention of pleasure. This means that a lot of people are still getting ideas about things from porn (which isn't good), meaning that there are people who do think that penetrating the cervix would be cool, good, and pleasurable instead of horrific and painful.
In terms of the origin of the trope though, it isn't really about the act itself, it's a heterosexual masculine power fantasy about being masculine enough and having the level of control over women's bodies that would allow one to penetrate that deeply. I think understanding this sort of "bad anatomy" not as the result of stupidity or ignorance, but through understanding the cultural and gendered forces that influence our sexual desires and practices and how people construct and "do" gender through sexual practices and depictions of them, is vastly more insightful and constructive.
All media says things about the socio-cultural context within which it was made. But often porn doesn't just say things, it yaps incessantly and refuses to shut the fuck up.
