As I’m making my way through the mid 20s, there’s been a lot of new kanji (kanjis?) about body parts (insert 金玉 joke here). When we initially learned in bio, diagrams really helped clarify and retain a lot of things - so here’s one:
From the site, the image is also clickable so you can go to the various words. They also have these for things like positions, winter/spring themed, clothes etc.
I noticed that 腰 is translated as waist but is usually used when talking about lower back, especially by elderly people complaining about pain.
For thighs there is anothe word: 太腿(ふともも)but it could aslo mean butt.