Yanagida was riding Te Atatu Pash in the last race at the Cambridge synthetic track meeting when his mount was brought down in the home straight and he landed heavily.
The popular jockey was knocked unconscious in the accident and was placed in an induced coma at the track before being transported to Waikato Hospital.
He was diagnosed there with head and spinal injuries and was moved to Middlemore Hospital in South Auckland.
Yanagida's manager Ted McLachlan was at Waikato Hospital with the jockey during his initial assessment and was among those left stunned by the fall.
"Taiki arrived here [around 7pm] and was taken straight to the ICU in an induced coma," said McLachlan.
"But after he was also diagnosed with spinal injuries he was transported to Middlemore and the doctors saying it could be four or five days before we know the extent of his head injuries."
Yanagida has been a big mover in the northern jockey ranks in the last two years and had a personal best season last term with 42 winners in his first year out of his apprenticeship.
He was born and raised in Japan, where his parents still live. They don't fluent speak English so are being kept updated on Taiki's condition by fellow Japanese jockey Yuto Kumagai, who like Yanagida is also now riding in Waikato.
Yanagida's parents are expected to fly to New Zealand, arriving on Friday morning to be with their son. New Zealand Thoroughbred Racing chief executive Bruce Sharrock has confirmed NZTR will pay for their flights.