...the connecting portion the function of which is to join the body to the head and to transmit to the body the influences and volitions of the head- We mean the neck. Yes, says St. Bernardine of Sienna, "she is the neck of Our Head, by which He communicates to His mystical body all spiritual gifts. "-Ad DiemI just see this as yet another place Mary is insinuated into Christ. Being the neck between the body and the head.
It gets much worse. Supposedly, Mary is also the Mediatrix of ALL Grace.
This is how Marian devotion works, IMHO:
(1)Jesus Himself is the perfection and summation of ALL the Grace of God.
(2)Mary "brought" Jesus to us, as the intermediary between God and parturition.
(3) Therefore etc.
I am going to try a little more in an answer to smvoice.