A biopsy apparatus, comprising: a driver assembly having a housing configured to be grasped by a user; a biopsy probe mechanism drivably coupled to said driver assembly, said biopsy probe mechanism including a biopsy cannula having a cylindrical side wall, a proximal end, a distal end and a longitudinal axis extending between said proximal end and said distal end, said cylindrical side wall defining a lumen and having a side port located near said distal end that extends through said side wall to said lumen; and a thumbwheel mechanism interposed between the driver assembly and the biopsy probe mechanism, said thumbwheel mechanism including: a thumbwheel drivably coupled to said biopsy cannula to rotatably position said side port of said biopsy cannula at a desired rotational position about said longitudinal axis relative to said driver assembly; a detent wheel mounted to said biopsy cannula for coaxial rotation with said biopsy cannula about said longitudinal axis, said detent wheel having a circumferential surface and a plurality of detent recesses (74-1,..., 74-N) formed through said circumferential surface and extending radially toward said longitudinal axis, said plurality of detent recesses (74-1,..., 74-N) being positioned about said longitudinal axis at predetermined angular positions; and an engagement device having an engagement element biased in constant engagement with said detent wheel, wherein as said biopsy cannula is rotated said engagement element rides along said circumferential surface of said detent wheel and produces at least one of a tactile and an aural feedback each time said engagement element engages one of said plurality of detent recesses (74-1,..., 74-N). a driver assembly having a housing configured to be grasped by a user; a biopsy probe mechanism drivably coupled to said driver assembly, said biopsy probe mechanism including a biopsy cannula having a cylindrical side wall, a proximal end, a distal end and a longitudinal axis extending between said proximal end and said distal end, said cylindrical side wall defining a lumen and having a side port located near said distal end that extends through said side wall to said lumen; and a thumbwheel mechanism interposed between the driver assembly and the biopsy probe mechanism, said thumbwheel mechanism including: a thumbwheel drivably coupled to said biopsy cannula to rotatably position said side port of said biopsy cannula at a desired rotational position about said longitudinal axis relative to said driver assembly; a detent wheel mounted to said biopsy cannula for coaxial rotation with said biopsy cannula about said longitudinal axis, said detent wheel having a circumferential surface and a plurality of detent recesses (74-1,..., 74-N) formed through said circumferential surface and extending radially toward said longitudinal axis, said plurality of detent recesses (74-1,..., 74-N) being positioned about said longitudinal axis at predetermined angular positions; and an engagement device having an engagement element biased in constant engagement with said detent wheel, wherein as said biopsy cannula is rotated said engagement element rides along said circumferential surface of said detent wheel and produces at least one of a tactile and an aural feedback each time said engagement element engages one of said plurality of detent recesses (74-1,..., 74-N). a thumbwheel drivably coupled to said biopsy cannula to rotatably position said side port of said biopsy cannula at a desired rotational position about said longitudinal axis relative to said driver assembly; a detent wheel mounted to said biopsy cannula for coaxial rotation with said biopsy cannula about said longitudinal axis, said detent wheel having a circumferential surface and a plurality of detent recesses (74-1,..., 74-N) formed through said circumferential surface and extending radially toward said longitudinal axis, said plurality of detent recesses (74-1,..., 74-N) being positioned about said longitudinal axis at predetermined angular positions; and an engagement device having an engagement element biased in constant engagement with said detent wheel, wherein as said biopsy cannula is rotated said engagement element rides along said circumferential surface of said detent wheel and produces at least one of a tactile and an aural feedback each time said engagement element engages one of said plurality of detent recesses (74-1,..., 74-N).