Jockey Blake Spriggs remains under observation in hospital with doctors monitoring a head injury after he fell at Hawkesbury.

Racing NSW said Spriggs also has a relatively undisplaced fracture to his patella which is unlikely to need surgery but will be further assessed with scans.

Spriggs was injured in the first race on Thursday and has been taken off rides at Goulburn and Randwick over the next two days.

He was conscious after the incident but had a laceration to an eye.