The rider, a man, received advanced trauma care by paramedics before being taken to hospital.
West Midlands Ambulance Service and the air ambulance were called to the crash in Northfield Road, Netherton, at around 1.15pm on Tuesday.
A spokesperson for West Midlands Ambulance Service said: "A passing PTS [patient transport service] high dependency crew came across the incident and stopped to render aid.
"An ambulance and the Midlands Air Ambulance from Cosford with a MERIT [medical emergency response intervention team] trauma doctor and critical care paramedic on board were sent to the scene.
"The motorcyclist, a man, sustained serious injuries in the collision and received advanced trauma care at the scene by the team of ambulance staff.
"Once stabilised the man was conveyed by land ambulance on blue lights to Queen Elizabeth Hospital Birmingham for further emergency care."