It is an honor for them to honor me. My attendance is not for my benefit but for theirs.

§ With regard to the halakha that a cut windpipe renders the animal a tereifa, Rav Yehuda says that Rav says: If the windpipe was perforated with a series of small holes around its circumference like a sieve, the small holes join together to constitute a majority of the circumference. Therefore, if their collective size is a majority of the circumference, the windpipe is considered cut.

Rav Yirmeya raises an objection: The mishna teaches (Oholot 2:3) that if a skull of a corpse has a round hole at least the size of a drill bit used for surgery, then the skull does not impart ritual impurity in a tent. With regard to this, a baraita states: And in a skull that contains one long hole, or even if it has many small holes, the areas of the holes join together to constitute the size of a drill hole. Evidently, since the requisite measure is the size of a drill hole, the small holes join together to constitute the size of a drill hole, and not another measure. If so, here, too, in the case of the windpipe, since the requisite measure of a hole to render the animal a tereifa is the size of an issar (see 54a), the small holes should join together to constitute the size of an issar. Why must they constitute the majority of the circumference?

The Gemara notes: It escaped him, i.e., Rav Yirmeya, that which Rabbi Ḥelbo says that Rav Ḥama bar Gurya says that Rav says: Perforations that are a deficiency, i.e., holes of significant area, join together to constitute the size of an issar, and perforations that are not a deficiency, but are as small as the holes of a sieve, must join together to constitute a majority of the circumference, which is the measure of a cut windpipe. Since the holes are not substantial in area, the windpipe cannot be said to be missing a piece, but it may be considered cut.

Rabba bar bar Ḥana says that Rabbi Yehoshua ben Levi says: If a strip of the windpipe was removed from it, its area joins to constitute the size of an issar, even if the strip itself is narrower than an issar. Rabbi Yitzḥak bar Naḥmani asked Rabbi Yehoshua ben Levi: If the windpipe was perforated like a sieve, what is the halakha? Rabbi Yehoshua ben Levi said to him: The Sages said with regard to this case: Perforations that are a deficiency join together to constitute the size of an issar, and perforations that are not a deficiency join together to constitute a majority of the circumference.

The Gemara raises a question: The measure of an issar for missing flesh in the windpipe applies only to animals. In birds, this cannot be the measure, as the entire width of the windpipe is less than the diameter of an issar. What, then, is the measure with regard to a bird?

Rabbi Yitzḥak bar Naḥmani said: It was explained to me personally by Rabbi Elazar: One severs the perforated tissue, folds and lays it over the opening of the windpipe. If it covers the majority of the windpipe, the animal is a tereifa; and if not, the animal is kosher. Rav Pappa said: And your mnemonic for this halakha should be a sieve. If the tissue is perforated like a sieve, one must place it over the opening of the windpipe as if it were a sieve.

The Gemara continues: If the windpipe was missing a piece so that its appearance was like a door, where the missing flesh was partially attached as though on a hinge, Rav Naḥman said: If the missing piece is so large that an issar can enter the hole widthwise, i.e., it is wider and taller than an issar, the animal is a tereifa. If the windpipe was cracked along its length, Rav said: Even if only one undamaged segment remains in the windpipe above the crack and one segment below it, the animal is kosher.

The Sages said this statement before Rabbi Yoḥanan, who said: What is this segment and what is that segment that Rav says? Segments are immaterial to the matter. Rather, say: Even if any amount remained intact in the windpipe above the crack, and any amount below, the animal is kosher.

The Sages said this statement in Eretz Yisrael before Rabbi Yoḥanan in the name of Rabbi Yonatan the Babylonian, i.e., that any amount of undamaged tissue above and below the crack renders the animal kosher. Rabbi Yoḥanan said to them, excitedly: Do our Babylonian friends know how to interpret in accordance with this explanation? He was happy that Rabbi Yonatan interpreted it the same way he did.

§ Rabbi Ḥiyya bar Yosef taught before Rabbi Yoḥanan: The entire neck is fit for slaughter, from the large uppermost ring of the windpipe downward until the lower edges of the lung. Rava says that the phrase: Lower edges of the lung, is referring to an animal hung by the feet; that is, it actually denotes the upper edges nearest the head. As I say that the area fit for slaughter is all the length of the neck that an animal extends in order to graze, provided that it is not forced to extend its neck further than it wishes. Consequently, the very bottom of the neck is not a location fit for slaughter.

Rav Ḥanina, and some say Rav Ḥananya, raises a dilemma: If the animal forced itself and extended its neck, what is the halakha with regard to the additional area? The Gemara responds: The question shall stand unresolved. The Gemara relates that Rabbi Yoḥanan and Rabbi Shimon ben Lakish sat together, and a matter emerged from between them: If the slaughterer forced the animal to extend the simanim by stretching the neck and slaughtered the animal at the lower end of the neck, the slaughter is not valid. And if the windpipe was perforated below the breast, it is considered to be like a perforated lung, which renders the animal a tereifa no matter the size of the perforation. A perforation in the upper windpipe must be the size of an issar to render the animal a tereifa (see 54a).

The Gemara elaborates: The Sages taught in a baraita: Which is the breast that must be given to the priests as a gift from every peace offering (see Leviticus 7:31)? This is the section that faces the ground, not the ribbed area on the sides. And lengthwise it extends below, when the animal is hung from the legs, until the neck, and above until the rumen. One cuts the two ribs nearest the head from the two sides of the animal from both directions, and this is the breast that is given to the priests.

§ The mishna states: If the membrane of the brain was perforated, the animal is a tereifa. The Gemara cites Rav and Shmuel, who both say: The brain is covered by two membranes, a thick outer membrane adjacent to the skull and a thin inner membrane adjacent to the brain. The animal is a tereifa if the outer membrane was perforated, even if the inner membrane was not perforated. And some say that the animal is not a tereifa unless the inner membrane was perforated as well. Rabbi Shmuel bar Naḥmani says: And this is your mnemonic to remember the halakha: The bag in which the brain rests, i.e., the inner membrane.

Rabba bar bar Ḥana says that Rabbi Yehoshua ben Levi says: Even though the inner membrane of the brain is very thin and not easily visible, its equivalent in the testicles, which are also enclosed in a thin membrane, is conspicuous, as it has an appearance different from the testicles themselves. Rabbi Shimon ben Pazi says that Rabbi Yehoshua ben Levi says in the name of bar Kappara: With regard to the brain, everything inside the skull is considered part of the brain. From the point where it begins to extend like a cord out of the base of the skull, it is considered the spinal cord. And from where does it begin to be extended? Rabbi Yitzḥak bar Naḥmani said: It was explained to me personally by Rabbi Yehoshua ben Levi himself: Protrusions similar to two