Sphincters are tight orifices found within the body or as the entrance/exit to a body. Due to the frequency of anal or oral, the tag limits its scope to sphincters found in more niche cases such as vore, endosoma or deep_peneration.

Examples:
- esophageal_sphincter: Used for both the upper and lower esophageal sphincter. The upper esophageal sphincter connects the throat to the esophagus. Meanwhile the lower esophageal sphincters connects the stomach to the esophagus.
- Pyloric_Sphincter: The sphincter which separates the stomach from the intestines.
- ileocecal_valve: The sphincter which separates the small intestine and the colon.