These words are found in some versions of the Sefer Yetzirah 5:6, and A. Kaplan comments on them on pages 212-214 of his translation and commentary of the same.
In there, he mentions that the Hemsess usually refers to the 'third-stomach' in ruminating animals, and used to grind food - and roughly corresponding in the human being to the small intestines.
The Korkeban, according to Kaplan, 'is most often used to denote the gizzard in fowl'. The Zohar apparently 'clearly' identifies it with the stomach.
The Kivah corresponds to the fourth stomach in ruminating animals, and perhaps the esophagus (according to an analogy explained by Maimonides).
In any event, what these three terms refer to is not clear, except that each is in some manner associated with parts of the digestive process or a digestive organ, and possibly not a human one.
Remembering that Kaplan has two and a half pages on these three words, I would, as with any discussion on the Sefer Yetzirah, highly recommend perusing his work directly.