We bow in the Amidah as it says in Sh O, O Ch 113 (1)
These are the blessings at which we bow: In the Shemoneh Esrei at the prayer of Avot and at the end, In Modim in the beginning and at the end.
I was told in a shiur that the purpose of bowing is to give homage. If so, the obvious questions are: why only these two blessings and why at the beginning and the end.
So my questions are:
(a) what is the purpose of the bowing in the Amida
(b) how does this reason explain why bowing is only for Avos and Modim
(c) why at the beginning and the end of these blessings?