Refers to the upper part of the leg between the hip and the knee. Used in both anatomical and everyday contexts.
昨日の運動で腿が痛い。
My thighs are sore from yesterday's exercise.
彼は腿にけがをした。
He injured his thigh.
I injured my thigh during the match.
My thigh cramped up after running for a long time.
I'm strengthening my thighs with squats.