A medical apparatus comprising: an arm having a proximal end portion connected to a stationary object and a distal end portion, a medial-lateral bar connected to the distal end portion of the arm and having a first arcuate rail; a cranial-caudal bar having: a first arcuate rail in slidable engagement with the first arcuate rail of the medial-lateral bar in a first direction, wherein the first arcuate rail of the cranial-caudal bar and the first arcuate rail of the medial lateral-bar have matching arcuate shapes, and a second arcuate rail extending substantially perpendicularly from the first arcuate rail of the cranial-caudal bar; a working channel construct comprising: a tube having an outer surface, a proximal end portion and a distal end, and a slider attached to the outer surface of the tube and having a first arcuate rail in slidable engagement with the second arcuate rail of the cranial-caudal bar, wherein the first arcuate rail of the slider and the second arcuate rail of the cranial-caudal bar have matching arcuate shapes; wherein the matching arcuate shapes of the first arcuate rail of the cranial-caudal bar and the first arcuate rail of the medial lateral-bar allow the tube to be tilted in a first plane, to define a medial-lateral tilt angle of the tube, while maintaining a location of the distal end of the tube; and wherein the matching arcuate shapes of the first arcuate rail of the slider and the second arcuate rail of the cranial-caudal bar allow the tube to be tilted in a second plane, to define a cranial-caudal tilt angle of the tube, while maintaining the location of the distal end of the tube. an arm having a proximal end portion connected to a stationary object and a distal end portion, a medial-lateral bar connected to the distal end portion of the arm and having a first arcuate rail; a cranial-caudal bar having: a first arcuate rail in slidable engagement with the first arcuate rail of the medial-lateral bar in a first direction, wherein the first arcuate rail of the cranial-caudal bar and the first arcuate rail of the medial lateral-bar have matching arcuate shapes, and a second arcuate rail extending substantially perpendicularly from the first arcuate rail of the cranial-caudal bar; a first arcuate rail in slidable engagement with the first arcuate rail of the medial-lateral bar in a first direction, wherein the first arcuate rail of the cranial-caudal bar and the first arcuate rail of the medial lateral-bar have matching arcuate shapes, and a second arcuate rail extending substantially perpendicularly from the first arcuate rail of the cranial-caudal bar; a working channel construct comprising: a tube having an outer surface, a proximal end portion and a distal end, and a slider attached to the outer surface of the tube and having a first arcuate rail in slidable engagement with the second arcuate rail of the cranial-caudal bar, wherein the first arcuate rail of the slider and the second arcuate rail of the cranial-caudal bar have matching arcuate shapes; a tube having an outer surface, a proximal end portion and a distal end, and a slider attached to the outer surface of the tube and having a first arcuate rail in slidable engagement with the second arcuate rail of the cranial-caudal bar, wherein the first arcuate rail of the slider and the second arcuate rail of the cranial-caudal bar have matching arcuate shapes; wherein the matching arcuate shapes of the first arcuate rail of the cranial-caudal bar and the first arcuate rail of the medial lateral-bar allow the tube to be tilted in a first plane, to define a medial-lateral tilt angle of the tube, while maintaining a location of the distal end of the tube; and wherein the matching arcuate shapes of the first arcuate rail of the slider and the second arcuate rail of the cranial-caudal bar allow the tube to be tilted in a second plane, to define a cranial-caudal tilt angle of the tube, while maintaining the location of the distal end of the tube.