A medical positioning apparatus (1, 100, 300) for positioning and holding an object, comprising: a telescopic member (102, 302) extending between a first end and a second end and having an adjustable length; a support member for receiving the object; a base member (2, 110, 112, 310) securable to a base; a first joint mechanism movably securing the support member to the first end of the telescopic member (102, 302); a second joint mechanism movably securing the base member (2, 110, 112, 310) to the second end of the telescopic member (102, 302), the first and second joint mechanisms each having at least two rotational degrees of freedom; a locking device (124, 126, 128, 324, 326, 328) operatively connected to the first and second joint mechanisms and the telescopic member (102, 302), the locking device (124, 126, 128, 324, 326, 328) operable between a locked position in which the support member, the base member (2, 110, 112, 310), and the telescopic member (102, 302) are lockingly interconnected together and the length of the telescopic member (102, 302) is fixed, and a released position in which the support and base members are free to pivotally move with respect to the telescopic member (102, 302) and the length of the telescopic member (102, 302) is adjustable, the locking device (124, 126, 128, 324, 326, 328) being passively biased in the locked position; and a lock activation device to unlock the locking device (124, 126, 128, 324, 326, 328) biased in the locked position in order to adjust the length of the telescopic member (102, 302) and a relative position of the support member, the base member (2, 110, 112, 310), and the telescopic member (102, 302), characterized in that the locking device (124, 126, 128, 324, 326, 328) comprises a first, second, and third locking units operatively connected to the first joint mechanism, the second joint mechanism, and the telescopic member (102, 302), respectively, and each passively biased in the locked position, wherein each one of the first, second, and third locking units comprises an elastic member, a piston (20, 34, 48, 66, 172, 188, 372), and a brake pad operatively connected together, the elastic member being passively compressed when the first, second, and third locking units are in the locked position, and being further actively compressed when the first, second, and third locking units are in the released position upon activation of the lock activation device. a telescopic member (102, 302) extending between a first end and a second end and having an adjustable length; a support member for receiving the object; a base member (2, 110, 112, 310) securable to a base; a first joint mechanism movably securing the support member to the first end of the telescopic member (102, 302); a second joint mechanism movably securing the base member (2, 110, 112, 310) to the second end of the telescopic member (102, 302), the first and second joint mechanisms each having at least two rotational degrees of freedom; a locking device (124, 126, 128, 324, 326, 328) operatively connected to the first and second joint mechanisms and the telescopic member (102, 302), the locking device (124, 126, 128, 324, 326, 328) operable between a locked position in which the support member, the base member (2, 110, 112, 310), and the telescopic member (102, 302) are lockingly interconnected together and the length of the telescopic member (102, 302) is fixed, and a released position in which the support and base members are free to pivotally move with respect to the telescopic member (102, 302) and the length of the telescopic member (102, 302) is adjustable, the locking device (124, 126, 128, 324, 326, 328) being passively biased in the locked position; and a lock activation device to unlock the locking device (124, 126, 128, 324, 326, 328) biased in the locked position in order to adjust the length of the telescopic member (102, 302) and a relative position of the support member, the base member (2, 110, 112, 310), and the telescopic member (102, 302), characterized in that the locking device (124, 126, 128, 324, 326, 328) comprises a first, second, and third locking units operatively connected to the first joint mechanism, the second joint mechanism, and the telescopic member (102, 302), respectively, and each passively biased in the locked position, wherein each one of the first, second, and third locking units comprises an elastic member, a piston (20, 34, 48, 66, 172, 188, 372), and a brake pad operatively connected together, the elastic member being passively compressed when the first, second, and third locking units are in the locked position, and being further actively compressed when the first, second, and third locking units are in the released position upon activation of the lock activation device.