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The sciatic nerve (gid ha-nasheh) is the largest tendon, and most of the leg’s nerves pass through it. It extends from the spinal cord to the end of the foot. The Torah prohibits eating the part of the nerve on the thigh of an animal’s rear legs. The fat adjacent to the nerve is prohibited as well, according to rabbinic law or custom. Removing all these prohibited parts is complex and requires training. This work is done by professionals at kashering (which is explained in the next section).
This prohibition was established in remembrance of Jacob’s struggle with the angel when he returned to the Land, a struggle in which the angel damaged his adversary's sciatic nerve (Genesis 32:22-32). It has been suggested this nerve symbolizes the transition from the good intentions and aspirations of the mind to the lust and physicality of the body’s lower parts. According to the Sages, the angel who wrestled with Jacob was Esau’s heavenly representative, which means he stood for the denial of human ability to improve the world and to live according to divine values. Accordingly, the angel attacked Jacob’s nerve to make him a prisoner of his baser desires. However, our father Jacob succeeded in holding his own throughout the night. At dawn, the angel finally conceded defeat. Similarly, the Jews would later succeed in holding onto their faith throughout the long exile until the dawn of redemption, when the divine light will shine forth and repair the entire world.
