Yosef Karo

“ And if there remains [unsplit] from it anything at all above and below the place that's fit for slaughtering, it is valid, because whenever the neck is drawn out the crack continues to close, therefore it will return [to normal] and be healed.
8 If it was punctured below the place [that is fit] for slaughtering, even a little bit, it is an invalid animal. ”

“ And if they do create a deficiency, they combine to [the measurement of] an issar coin, that if there is [the measurement of] an issar coin with [all of the] holes and the complete [part of the windpipe] between them, it is forbidden; and this is when the holes are very close together that there isn't between one hole and the next the size of a hole, but if there is between [each hole] more than this measurement [then] what [part of the windpipe] that is between them does not combine. ”