JT McNamara has undergone surgery on the serious neck injury he sustained in a fall at Cheltenham on Thursday.
The 37-year-old was injured in a first fence fall from Galaxy Rock in the Fulke Walwyn Kim Muir Challenge Cup.
McNamara, one of the leading amateurs on the circuit for a number of years, was airlifted to hospital after being treated by the on-course medics.
Conscious following the fall according to officials at the track, he was put in an induced coma before his transfer to Frenchay Hospital in Bristol.
Dr Adrian McGoldrick, chief medical officer of the Irish Turf Club, has issued an update on the rider and his condition remains serious but stable.
McGoldrick said: "We can confirm that amateur rider JT McNamara suffered two fractured vertebrae in his neck.
"He is currently in theatre at Frenchay Hospital in Bristol. There will be no further news until tomorrow and we will keep everyone updated.
"His wife Caroline is with him."
Cheltenham, the British Horseracing Authority and Jonjo O'Neill, the trainer of Galaxy Rock, have agreed the Injured Jockeys Fund will issue further information on the rider's condition when appropriate.