Ana O'Brien, the daughter of trainer Aidan, suffered a fractured C1 vertebra in her neck and T6 in her back after a fall at Killarney on Tuesday evening that saw her taken to hospital by air ambulance.
O'Brien, 21, was quickly attended to after her mount Druids Cross, trained by her brother, Joseph, slipped up over two furlongs out in the Celtic Steps The Show At Killarney Racecourse Rated Race, the second contest on the card which was run at 6.20pm.
The three-year-old Druids Cross was fatally injured, while O'Brien was taken off the track in an ambulance before being transferred to Cork University Hospital, the Irish Coast Guard air ambulance arriving at 7.45pm and landing on the golf course in the middle of the circuit.
The third race was delayed for well over an hour as a result, although the meeting was completed, with the last race run at around 9.20pm.
Turf club chief medical officer Dr Adrian McGoldrick was among those who attended O'Brien, and he said: "Ana's brain scan is clear.
"She has a fractured C1 vertebra in her neck and T6 in her back. Both will have an MRI scan tomorrow to assess further. She has fractured cheek bones bilaterally. Aidan and AnneMarie (O'Brien) would like to thank the superb work provided to Ana by the Order Of Malta, racecourse doctors, veterinary team and ground staff led by Val O'Connell (clerk of the course). Also the Air Medical Crew and the amazing staff at CUH."
McGoldrick added he expected O'Brien, who rode in both the English and Irish Derbys for her father this season and partnered her first winner as a 16-year-old at Dundalk in February, 2013, to have a recovery period of between three to four months.
Champion jockey Ruby Walsh, who claimed the final event on 7-4 favourite Conrad Hastings, earlier told At The Races after supervising the win of the Willie Mullins-trained Grainne's Dream in the delayed 6.50: "I think the news was a bit better when she was leaving, so hopefully that is right.
"She'll be well looked after, fingers crossed for her."