A table adapter and joint assembly are configured for use with a table during a medical procedure, e.g. a medical imaging procedure or combined imaging and surgical procedure. The table adapter is connectable, directly or indirectly, to a portion of the table. The joint assembly connects with the table adapter about a shaft such that the joint assembly is rotatably adjustable. A head fixation device in the form of a skull clamp is attachable to the joint assembly. The joint assembly generally has a parallelogram shape that has four joints for adjustment where these four joints can be selectively locked or unlocked relative to each other using a single actuator.
