c is respectively individually connected with second arm part 30 for the sake of which a slot 84 a c is provided in block 78 for each end 82 a c respectively in which the respective end 82 a c is secured into and via tubular member 76 is connected with block 78 in such a way that it resists extension ends 82 a c are in this connection again laid into loops which by means of a squeezing device or a ring are secured against detaching in an alternative embodiment instead of fixing ends 82 a c individually in block 78 for the sake of which three slots 84 a c are provided it can also be provided to collect ends 82 a c to one single end e g by bunching or bundling by means of a squeezing device or a squeezing ring and then attach this collected end onto block 78 for the sake of which only one of the slots 84 a c needs to be there on end 38 of second arm part 30 a fixation element 86 is arranged over which second arm part 30 is connected articulatedly with extension bar 40 according to fig1 traction elements 60 a c are flexible so that they can adjust in the region of articulation 32 when articulated arm 24 is bent to the curved transition from first arm part 28 to.