Popliteal fossa (English spelling) poplitealfossa

…the front of the knee is called the anterior knee, and the part of it that corresponds to the patella is called the patella (also called the kneecap). The back is called the posterior knee, and in the center there is a depression called the popliteal fossa (also called the kneecap). The popliteal fossa forms a triangle with its apex pointing upward, and its two sides are made up of the lower ends of the semitendinosus and semimembranosus muscles and the lower end of the biceps femoris, and the base is made up of the origin of the gastrocnemius muscle.

*Some of the terminology that mentions "popliteal fossa" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ひざの前面は前膝部といい，このうち膝蓋骨に相当した部分を膝蓋部(いわゆる膝頭)という。また後面を後膝部といい，この中央にはへこんだ膝窩（しつか）popliteal fossa(いわゆる〈ひかがみ〉)がある。膝窩は上方に頂点を向けた三角形をなすが，この2辺は半腱様筋および半膜様筋の下端と大腿二頭筋の下端からなり，底辺は腓腹筋の起始部からなる。…

※「popliteal fossa」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報