Yosef Karo, Shulchan Aruch — 41: Laws of Treifot of the liver
“ A needle that's found in the liver whether it's entered whole or broken - if its blunt end is toward the beast's cavity outwards it's treif, even if it's all buried in the flesh of the liver, for we are concerned it entered through the esophagus to the intestines and exited the intestines to the beast's cavity and pierced it from there and entered in the liver, for if it entered through the bronchiae its blunt end would be unable to pierce it. ”
