Robbie McNamara is in a stable condition and in "high spirits" after undergoing spinal surgery at the Mater Hospital in Dublin yesterday.
The jockey was due to partner last year's Cheltenham Gold Cup winner Lord Windermere in the Crabbie's Grand National at Aintree, but suffered multiple injuries after coming to grief in a fall at Wexford.
He was initially taken to Wexford General Hospital, before being transferred on Friday night.
Dr Adrian McGoldrick, chief medical advisor for the Irish Turf Club, said that it was too early to know the full extent of the injuries.
"He was very stable overnight and in very good spirits," he said. "He doesn't want to say any more at this stage and you can understand that."
"It was serious chest, abdominal and spinal injuries. The spinal injuries have been operated on and that's stabilised.
"The next phase is recuperation and we'll take it from there."
McNamara was transferred to the Mater hospital from Wexford General Hospital and trainer Jim Culloty yesterday confirmed that the rider had undergone surgery to remove a haematoma pressing on his spinal cord.
"My heart is thinking of Robbie McNamara at the moment," Culloty told Channel 4 Racing before the Grand National. "He is in surgery at the minute. As well as eight broken ribs and a punctured lung, he fractured his T11 vertebrae and there is a bit of spinal damage.
"There is a big haematoma on his spine pressing on his spinal cord and they are trying to remove that at the moment. My prayers are with him."
McNamara, who rode a double at last year's Cheltenham Festival as an amateur before turning professional earlier this season, was partnering 14-1 shot Bursledon when he came to grief four flights from the finish in the first division of the Cahore Point Handicap Hurdle.
He was taken to Wexford General Hosptial, where he underwent a CT scan, before being transferred to the Mater where he underwent surgery yesterday.