Rabbi Yehoishophot Oliver commented to "Chabad - Soul is actually a part of G-d/Tanya":
Re Tanya ch. 2: It's a bit hard, but once you learn it several times it becomes more clear. Here is an article that explains it somewhat in Hebrew:
This is the basic pshat as I understand:
The ben comes from the tipa, which comes from moach ha’av. In the ben himself, the division into different limbs comes only from the stay in the womb of the mother. However, that is not the core of the ben; the true core of the ben is the tipa. However, even once born, in the moach ha’ben there is an open revelation of the connection of the ben with its original source, the moach ha’av. Thus, every individual limb of the body, even the toenails, remains connected with its original source, the moach ha’av, through its connection to the moach ha’ben.
The moach ha’av refers to Chochmah of Atzilus, which is the original shoresh of neshomos Yisroel, the ben.
There are many different levels of neshomos, corresponding to the degree that the different neshomos are affected by the worlds (Beriah, Yetzirah, and Asiyah) as they pass through them on their way into their respective bodies in this lowly world.
As is known, the Jewish people correspond to a body. Some Jews are feet, for they excel in good deeds, etc.. All neshomos stem from the head, however. As is known, the heads of the neshomos Yisroel are the tzadikim. In them the shoresh of neshomos Yisroel in Chochmah of Atzilus shines openly (due to their tremendous bittul to rotzon Hashem). Thus, all Jews connect with their source in Chochmah of Atzilus through connecting with the Tzadikim.
This is the deeper meaning of the Ma’amar Chazal “u’ledovko boi,” that through connecting with talmidei Chachomim, one connects to the Shechinah.
Here is a letter of the Rebbe discussing the inyan on a more advanced level: