Leading apprentice Tegan Harrison was knocked out and taken to hospital with concussion after a race fall at Doomben on Wednesday.
Harrison was thrown from the saddle when her mount Egyptian Tomb was checked and blundered near the 300m mark in the Mt Franklin Sparkling Plate (1350m).
Harrison was taken by ambulance to St Andrews Private Hospital for observation after suffering concussion, neck soreness and minor facial injuries.
Stewards took evidence from jockey Andrew Spinks and apprentice Geoffrey Goold before adjourning the inquiry until Harrison is available.
Harrison has ridden 44 city winners this season and is running second to Michael Cahill on the Brisbane jockeys' premiership.