Yosef Karo, Shulchan Aruch — 56 Laws of treifot at the Tzomet haGiddim
“ And whoever is versed in determining its span, can measure any bird in proportion to its size. Wherever it's hard it's Tzomet haGiddim and wherever it's soft it's not Tzomet haGiddim (Piskei Mharai #141) . ”
Yosef Karo, Shulchan Aruch — 56 Laws of treifot at the Tzomet haGiddim
“ The thick sinew is the one that they part when they hang the beast and it lies over the two, and they're stick to the flesh and bone (Morekhai in the name of Rabya) . 8 In a bird they are on the middle bone [drumstick] like on a beast, 16 of them, and if the majority of one of them is severed it's treif (Ramban and Ran) . ”
Yosef Karo, Shulchan Aruch — 56 Laws of treifot at the Tzomet haGiddim
“ But we are not versed in measuring Tzomet haGiddim in birds because it's hard to check and easily treiffed, therefore whenever there's a wound at the Tzomet haGiddim, even if it's just swollen and bruised, since it would need checking and we're not versed in birds - it's treif (Mordekhai ...) ”
