it says that each part of the body corresponds to a specific part of the Torah and specific mitzvot etc, so which part does the skin correspond to? what about the neck? thanks

Shalom, Thank you for your question. You are correct that according to our teachings, there is a connection and correspondence between the commandments and the human body. We are taught that there are 613 commandments, which are comprised of 365 negative commands and 248 positives. The Talmud (Makot 23a- 24b) writes “Rabbi Simlai taught: There were 613 mitzvot stated to Moses in the Torah, consisting of 365 prohibitions corresponding to the number of days in the solar year, and 248 positive mitzvot corresponding to the number of a person’s limbs.” Based on this, kabalistic teachings have tried to relate specific commands to specific limbs. However, the simple reading of the Talmud does not necessarily imply that there is a one to one correspondence. Rather, that the commandments in their entirety build a perfect “body”. I am unaware of any listing of the kabbalistic efforts to relate the commandment to particular limbs. The work “Sefer Haradim” does list many commands that are connected to certain limbs – such as which mitzvot are preformed with the eyes, which with the heart etc. But, this is not a list of which commands relate to which limb – rather which commands are fulfilled with which body parts. So, after this introduction, I must leave you without an answer (although I am pretty certain that “skin” is not a limb, and so has no corresponding command). Blessings.