The QAS spokesman said she also had suspected bleeding on the brain.

Police at the scene of an accident at Deagon in which a cyclist was knocked off a bike. Credit:Seven News

Police investigating the collision have appealed for any witnesses to come forward, saying the cause of the crash was unclear.

It occurred just near the Gateway Motorway overpass, about 20 kilometres north of the Brisbane CBD.

Investigators have spoken with the 31-year-old truck driver.