A person is allowed to send a non-Jew a full thigh of a slaughtered kosher (ritually fit) animal that still has the Gid HaNasheh (sciatic nerve) inside it. We’re not nervous that another Jew is going to see the gift, want to buy it from the non-Jew, and eat it without removing the Gid HaNasheh, thinking it was already removed. But the reason is that, bottom line, you could look at it. When you look at the thigh, you can see very clearly. It’s recognizable whether the Gid HaNasheh was removed or not. If it was removed, the thigh would be cut open and everything would be removed. And therefore, in this case, the thigh is whole and wasn’t cut open, so it would be very obvious that the Gid HaNasheh is still in it.
The entire Gid HaNasheh has to be removed and rooted out, even the part that’s deeply embedded in the meat. Rabbi Yehuda says no, you don’t have to remove everything. It’s enough to fulfill the mitzvah (commandment) of removing some of it. As long as you remove the part that’s under the surface of the thigh, you’re okay. You did what you needed to do. The part that’s embedded deeply within the meat is permitted according to the opinion of Rabbi Yehuda.