A 49-year-old Grayslake man was in critical but stable condition after the motorcycle he was driving struck a raised center median Thursday morning on Route 12 in unincorporated Lake County near Palatine.

The man was traveling south on Route 12 near Plum Grove Road about 5:40 a.m. when, for unknown reasons, his motorcycle struck the roadway’s median, according to Lake County sheriff’s Detective Chris Covelli.

Lake County deputies found the man unconscious at the scene. The man was not wearing a helmet, and it appears his head struck the pavement, Covelli said.

He was taken to Advocate Lutheran General Hospital in Park Ridge.

Authorities are not releasing the man’s name while the investigation is ongoing.