A medical instrument comprising: a plurality of input spindles (221, 222, 223, 224); a plurality of first cables (241B, 242B, 243B, 244B); a plurality of second cables (241A, 242A, 243A, 244A), one of each cable of the first and second plurality of cables (241A, 242A, 243A, 244A, 241B, 242B, 243B, 244B) being wrapped around a corresponding input spindle of the plurality of input spindles (221, 222, 223, 224); a chassis in which the plurality of input spindles (221, 222, 223, 224) is mounted; an instrument shaft comprising a first end and a second end, the instrument shaft extending from the chassis at the first end; a mechanical structure coupled to the second end of the instrument shaft, the mechanical structure having a plurality of degrees of freedom of motion, the plurality of first cables and the second cables (241A, 242A, 243A, 244A, 241B, 242B, 243B, 244B) being connected to the mechanical structure such that rotations the plurality of input spindles (221, 222, 223, 224) actuate the plurality of degrees of freedom; a plurality of first pulleys (261, 262, 263, 264) mounted at a first level on the chassis, the plurality of first pulleys (261, 262, 263, 264) receiving the plurality of first cables (241B, 242B, 243B, 244B) from the plurality of input spindles (221, 222, 223, 224) and redirecting the plurality of first cables (241B, 242B, 243B, 244B) into and through the instrument shaft; and a plurality of second pulleys (251, 252, 253, 254) mounted at a second level on the chassis different from the first level, the plurality of second pulleys (251, 252, 253, 254) receiving the plurality of second cables (241A, 242A, 243A, 244A) from the plurality of input spindles (221, 222, 223, 224) and redirecting the plurality of second cables (241A, 242A, 243A, 244A) through the first level and into and through the instrument shaft. a plurality of input spindles (221, 222, 223, 224); a plurality of first cables (241B, 242B, 243B, 244B); a plurality of second cables (241A, 242A, 243A, 244A), one of each cable of the first and second plurality of cables (241A, 242A, 243A, 244A, 241B, 242B, 243B, 244B) being wrapped around a corresponding input spindle of the plurality of input spindles (221, 222, 223, 224); a chassis in which the plurality of input spindles (221, 222, 223, 224) is mounted; an instrument shaft comprising a first end and a second end, the instrument shaft extending from the chassis at the first end; a mechanical structure coupled to the second end of the instrument shaft, the mechanical structure having a plurality of degrees of freedom of motion, the plurality of first cables and the second cables (241A, 242A, 243A, 244A, 241B, 242B, 243B, 244B) being connected to the mechanical structure such that rotations the plurality of input spindles (221, 222, 223, 224) actuate the plurality of degrees of freedom; a plurality of first pulleys (261, 262, 263, 264) mounted at a first level on the chassis, the plurality of first pulleys (261, 262, 263, 264) receiving the plurality of first cables (241B, 242B, 243B, 244B) from the plurality of input spindles (221, 222, 223, 224) and redirecting the plurality of first cables (241B, 242B, 243B, 244B) into and through the instrument shaft; and a plurality of second pulleys (251, 252, 253, 254) mounted at a second level on the chassis different from the first level, the plurality of second pulleys (251, 252, 253, 254) receiving the plurality of second cables (241A, 242A, 243A, 244A) from the plurality of input spindles (221, 222, 223, 224) and redirecting the plurality of second cables (241A, 242A, 243A, 244A) through the first level and into and through the instrument shaft.