A passive holding arm for medical purposes, in particular for holding surgical mechatronic assistance systems and/or surgical instruments, comprising a proximal end for attaching the holding arm to a base and a distal end for receiving a surgical mechatronic assistance system and/or surgical instrument; at least one first and one second arm segment (12, 14), wherein the first arm segment is connected to a first joint and the second arm segment is connected to a second joint, wherein each joint (13, 15) is actively braked but not driven and is releasable and lockable, wherein each of the first and second joints (13, 15) thereto comprises an electromagnetic brake (60, 62) having a permanent magnet, wherein the brakes (60, 62) are biased in an unpowered idle state in such a way that the joints (13, 15) are locked; and an operating unit for bringing the holding arm into a desired pose, wherein the operating unit is adapted to release the associated joint (13, 15) upon contact between an operator and one of the first and second arm segments (12, 14), such that the first joint is released when a contact occurs between an operator and the first arm segment the second joint is released when contact occurs between the operator and the second arm segment; a first interface at the proximal end for connecting the holding arm to an energy source and to an external control unit for transmitting signals to and from the holding arm; wherein data can be provided about a pose of the holding arm at the first interface to transfer them at a surgical navigation system; a second mechatronic interface at the distal end for coupling the holding arm to the assistance system for controlling the assistance system; and a transmission unit (76, 78) which is arranged inside the holding arm and which connects the first interface to the second interface in order to transmit energy and signals between the interfaces (6, 8). at least one first and one second arm segment (12, 14), wherein the first arm segment is connected to a first joint and the second arm segment is connected to a second joint, wherein each joint (13, 15) is actively braked but not driven and is releasable and lockable, wherein each of the first and second joints (13, 15) thereto comprises an electromagnetic brake (60, 62) having a permanent magnet, wherein the brakes (60, 62) are biased in an unpowered idle state in such a way that the joints (13, 15) are locked; and an operating unit for bringing the holding arm into a desired pose, wherein the operating unit is adapted to release the associated joint (13, 15) upon contact between an operator and one of the first and second arm segments (12, 14), such that the first joint is released when a contact occurs between an operator and the first arm segment the second joint is released when contact occurs between the operator and the second arm segment; a first interface at the proximal end for connecting the holding arm to an energy source and to an external control unit for transmitting signals to and from the holding arm; wherein data can be provided about a pose of the holding arm at the first interface to transfer them at a surgical navigation system; a second mechatronic interface at the distal end for coupling the holding arm to the assistance system for controlling the assistance system; and a transmission unit (76, 78) which is arranged inside the holding arm and which connects the first interface to the second interface in order to transmit energy and signals between the interfaces (6, 8).