Dr Adrian McGoldrick, chief medical advisor for the Irish Turf Club, said: "Robbie has chest, abdominal and spinal injuries and has been transferred to Mater (Hospital).
"I have spoken to his family and we have agreed there will be no further comment until Sunday, by which time he will have undergone further scans."
"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.
Guy Disney became the first rider with a prosthetic leg to ride a winner when Gotoyourplay triumphed in the Men's Open at the Teme Valley point-to-point at Brampton Bryan.The inspirational Disney, 32, lost the bottom half of his right leg after his armoured vehicle was attacked in Afghanistan in 2009.