We are continuing in Tractate Chullin, chapter 6, Mishnah 7, with the list of disqualifying blemishes. The Mishnah opens: "Baal chamesh raglayim o she'ein lo ela shalosh" - an animal of the Kodashim, a cow, goat, or sheep, that was born with five legs, or conversely, has only three. In both of these cases, this is a complete blemish.
Regarding the extra leg, we must distinguish between two situations:
The extra leg is in the front: It is permissible to slaughter the animal and eat its meat.
The extra leg is in the back: The animal is a treifah. Although it is permissible to slaughter it, it cannot be eaten, and its meat may only be fed to dogs.
"Vesheraglav kelutos keshel chamor" - an animal whose hooves are round like those of a donkey is also included among the blemished animals. The Mishnah continues and lists: "Vehashachul vehakesul".
What are the shachul and kesul?
"Eizehu shachul? Shenishmetah yereicho" - the term 'shachul' in Aramaic means drawn or pulled out. The reference is to the thigh bone connecting to the animal's pelvis, in the flank area, which has popped out and become dislocated from its joint. This dislocated thigh protrudes from the side, giving the animal a strange appearance, and this is a permanent blemish.
"Vekesul - sha'achas miyerchosav gevohah" - the word is derived from 'kesel', which is the flank and inner thigh. The meaning is that one of the two thigh bones, and sometimes even both of them, protrudes upward and is connected too high in the flank area, like a sort of hump.
This appearance is deformed: the thigh is too high in the back in the shape of a hump, and this too is considered a permanent blemish, on account of which it is permissible to slaughter the animal outside the Temple and eat its meat.
In summary: In this Mishnah we learned four additional blemishes: an animal with five legs or only three legs (and regarding the extra leg - in the front it is permitted to be eaten, and in the back the animal is a treifah); hooves that are round like a donkey's; shachul - a thigh dislocated from its joint; and kesul - a thigh that is high and protrudes upward. All of these are permanent blemishes, which permit the slaughter of the animal outside the Temple.