Medical or dental-medical treatment chair or a head support for such a treatment chair

摘要

A medical or dental-medical treatment chair has a backrest and a head support. The head support is pivotally connected with the backrest by means of a joint device having a first joint, and being fixable in a respective pivot position by means of a fixing device. For improving the support function, the fixing device has a piston cylinder with two working chambers. The piston cylinder is connected with joint parts of the first joint. The working chambers are connected with one another by means of a connection line in which a valve is disposed that can be selectively opened and closed. An actuating member is provided for the selective opening and closing of the valve.