The slokah actually reads,:
Sadashiva samarambham Shankaracharya madhyagam(it is not madhyamam)
asmadacarya paryantam vande aguru paramparam!!
and on vyasa,
Shankaram Shankaracharyam kesavam Badarayanam!
sutra bhashya krtau vande Bhagavantau punah punah!!
N.Srikanta.