膝しっ膕かくMeanings1nounpopliteal fossa; back of the kneerare termanatomyRare anatomical term for the hollow at the back of the knee; the more common term is 膝窩 (しっか).See also: 膝窩膝しっ膕かくは膝ひざの裏うら側がわのくぼみを指さす医い学がく用よう語ごです。膝膕 (しっかく) is a medical term for the hollow on the back side of the knee.