antestomach

noun3

1. •
   A cavity that leads into the stomach, as in birds.
2. •
   The first stomach of a ruminant.

   • The physiological significance of microorganisms in the antestomach of ruminants . — 1926
3. •
   The lower portion of the esophagus in an animal that has a sphincter controlling the entrance of food from the esophagus into the stomach, especially when that portion of the esophagus is distended or dilated.

   • He had attempted to produce cancer in the antestomach of the rats, by painting them with tar in or around the mouth. — 1949