An animal’s hindlegs severed מן הארכובה ולמטה or מן הארכובה ולמעלה

The next Mishnah states: בהמה שנחתכו רגליה מן הארכובה ולמטה – an animal whose hindlegs were severed below the joint is kosher, but if they were severed מן הארכובה ולמעלה – from above the joint, it is a tereifah. Amoraim discuss which of the three leg bones was severed, the cannon (lower), shank (middle), or thigh (upper). Rav Yehudah said that "למטה" means למטה מן הארכובה – directly below the joint, and "למעלה" means למעלה מן הארכובה – directly above the joint. This "ארכובה" refers to the ארכובה הנמכרת עם הראש – the joint customarily sold along with the head, i.e., the lower leg joint (the tarsus, between the shank and cannon bones). Thus, if the leg is severed anywhere on the shank or thigh bone, it is a tereifah. Ulla said the ארכובה refers to the one כנגדו בגמל ניכר – whose parallel in a camel is noticeable, i.e., the upper joint (the patella, between the shank and thigh bones). Accordingly, a severed shank bone would still be kosher. Rav Pappa quotes another version of Rav Yehudah’s statement, in which he says that "למטה" means well below the (upper) joint, and even below the צומת הגידין (on the cannon bone). This version agrees with Ulla.

•  צומת הגידין

The Mishnah taught that ניטל צומת הגידין – if the junction of sinews on the hindleg was removed, it is a tereifah. This refers to מקום שהגידין צומתין בו – the place where the sinews converge, and the Gemara presents numerous opinions as to its precise location. Ameimar said it is made up of three strands of sinew, חד אלימא ותרי קטיני – one thick and two thin. If the thick one is severed, אזדא רוב בנין – the structural majority is lost. If the two thinner sinews are severed, אזדא רוב מנין – the numeric majority of sinews is lost. In either case, it is a tereifah. Mar bar Rav Ashi taught this ruling leniently: if the thick one is severed, האיכא רוב מנין – there is still the numeric majority, and if the thin ones were severed, the structural majority still remains, and the animal is not a tereifah. Rav said the צומת הגידין is a tereifah ברובו – through its majority, meaning רוב אחד מהן – most of any one of the sinews. However, Shmuel said that even if one is completely severed, הא איכא תרי – there are still two, and it is kosher. In another version, Rav said it is a tereifah when רוב כל אחד ואחד – most of every [sinew] is severed, and Shmuel said that even if a third of each sinew remains, it is kosher.

•  נשבר העצם

The Mishnah stated: נשבר העצם – if the bone was fractured, then אם רוב הבשר קיים – if most of the meat remains, the shechitah permits the limb, but if not, the shechitah does not permit the limb (even if the animal is not a tereifah). A Baraisa elaborates that if the bone was fractured ויצא לחוץ – and broke out through the skin, אם עור ובשר חופין את רובו – if the skin and meat cover most of it, it is permitted, but if not, it is prohibited. Rebbe Yochanan defined "רובו" as רוב עוביו – most of [the bone’s] thickness, but others said it is רוב הקיפו – most of [the bone’s] circumference. Therefore, Rav Pappa required a majority of both the thickness and the circumference. Amoraim discuss if עור הרי הוא כבשר – skin is the equivalent of meat, i.e., the “majority” may be composed of skin alone, or עור מצרף לבשר – skin may be combined with meat (i.e., equal parts skin and meat), or just עור משלים לבשר – skin may complete a majority which is primarily from meat.