how the bit controls the mouth

here are a few drawings on how the horses mouth and neck would react to the bit. there is not much expression except for the smiling head. i think it isn't hard to express emotion with a bit in the mouth (even though dreamworks drew bits in their mouth they didn't appear to have any during expressions. it appeared as if they wore hackamores) except for the "oh" expression any other one can be drawn with a bit in the mouth. but if you prefer, you can draw hackamores.