When referring to the lumen of the stomach is that just the opening. As in where are the HCl is and where your food enters? I googled the definition of lumen and it says inside space. I'm just not too clear on what it really means. Thanks.
Try more specific key words, like "lumen of the stomach."
http://www.google.com/search?client=safari&rls=en&q=lumen+of+the+stomach&ie=UTF-8&oe=UTF-8