Fastening unit for fastening a device for supporting a patient to be x-rayed to an operating table

A fastening device is disclosed. The fastening device has a housing having a receptacle that receives a coupler of an operating table device and a locking member connected to the housing and movable relative to the housing between a locked position and an unlocked position. The locking member retains the coupler in the receptacle in the locked position, and the locking member releases the coupler from the receptacle in the unlocked position. The fastening device also has a resilient member that urges the locking member toward the locked position, an actuation member that moves the locking member from the locked position to the unlocked position, and a ratchet assembly that maintains the locking member in the unlocked position.