Spinal needle

Claim 2

A spinal needle comprising a hollow outer needle having an outer surface a stylet removably insertable within said hollow outer needle said stylet forward end and said outer needle forward end cooperating in the extreme forward position of said stylet to provide a generally closed piercing end said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an acute angle with the longitudinal axis of said spinal needle and intersecting one another at an acute angle to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form two curved cutting edges which intersect to form a point said heel face being inclined at an angle to the longitudinal axis of said spinal needle and joining said side bevel faces and said straight cutting edge, said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said cutting edge extending from one-half to three-quarters of said dimenSion.

Claim 3

A spinal needle as claimed in claim 1 wherein said side bevel faces intersect one another at an angle of 55* to 85*.

Claim 4

A spinal needle as claimed in claim 1 wherein said heel face is inclined at an angle of 15* to 21* to said longitudinal axis.

Claim 5

A spinal needle comprising a hollow outer needle having a forward end with a cylindrical bore and cylindrical outer surface a stylet removably insertable within said hollow needle to an extreme forward position and fitting closely within said bore said stylet forward end and said outer needle forward end cooperating in said extreme forward position to provide a generally closed piercing end said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an acute angle of 15* to 21* with the longitudinal axis of said spinal needle and intersecting one another at an acute angle of 55* to 85* to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form curved cutting edges which intersect to form a point said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said heel face being inclined at a shallow angle to the longitudinal axis of said spinal needle and joining said side bevel faces and said cutting edge remote from said point to define the length of said straight cutting edge as about one-half to three-quarters of said dimension.

Claim 6

A spinal needle comprising a hollow outer needle having a forward end with a cylindrical bore and cylindrical outer surface a stylet removably insertable within said hollow needle to an extreme forward position and fitting closely within said bore said stylet forward end and said outer needle forward end cooperating in said extreme forward position to provide a generally closed piercing end said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an acute angle of 15* to 21* with the longitudinal axis of said spinal needle and intersecting one another at an acute angle of 55* to 85* to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form curved cutting edges which intersect to form a point said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said heel face being inclined at a shallow angle to the longitudinal axis of said spinal needle and joining said side bevel faces and said cutting edge remote from said point to define the length of said straight cutting edge as about one-half to three-quarters of said dimension.

Claim 7

A spinal needle as claimed in claim 4 wherein said heel face is inclined at an angle of 15* to 21 degrees to said longitudinal axis.

Claim 8

A spinal needle comprising a hollow outer needle having a hub and a forward end, said forward end having a cylindrical bore and cylindrical outer surface a stylet removably insertable within said hollow needle to an extreme forward position and having a hub and a cylindrical forward end and fitting closely within said bore said stylet forward end and said outer needle forward end cooperating in said extreme forward position to provide a generally closed piercing end locking means for limiting said inserted stylet to a single predetermined angular position with respect to said outer needle in said extreme forward position said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an identical acute angle of 15* to 21* with the longitudinal axis of said spinal needle and intersecting one another at an actue angle of 55* to 85* to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form curved cutting edges which intersect to form a point said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said heel face being inclined at an angle of 15* to 21* to the longitudinal axis of said spinal needle and joining said side bevel faces at equal angles thereto remote from said point to define said straight cutting edge as about one-half to three-quarters of said dimension.

Claim 9

A spinal needle comprising a hollow outer needle having a hub and a forward end, said forward end having a cylindrical bore and cylindrical outer surface a stylet removably insertable within said hollow needle to an extreme forward position and having a hub and a cylindrical forward end and fitting closely within said bore said stylet forward end and said outer needle forward end cooperating in said extreme forward position to provide a generally closed piercing end locking means for limiting said inserted stylet to a single predetermined angular position with respect to said outer needle in said extreme forward position said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an identical acute angle of 15* to 21* with the longitudinal axis of said spinal needle and intersecting one another at an actue angle of 55* to 85* to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form curved cutting edges which intersect to form a point said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said heel face being inclined at an angle of 15* to 21* to the longitudinal axis of said spinal needle and joining said side bevel faces at equal angles thereto remote from said point to define said straight cutting edge as about one-half to three-quarters of said dimension.

Claim 10

A spinal needle comprising a hollow outer needle having an outer surface a stylet removably insertable within said hollow outer needle said stylet forward end and said outer needle forward end cooperating in tHe extreme forward position of said stylet to provide a generally closed piercing end said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an acute angle with the longitudinal axis of said spinal needle and intersecting one another at an acute angle to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form two curved cutting edges which intesect to form a point, each said side bevel face including a rounded end remote from said point, said heel face being inclined at an angle to the longitudinal axis of said spinal needle and joining said side bevel faces, said heel face having a pointed forward edge joining said straight cutting edge, said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said cutting edge extending from one-half to three-quarters of said dimension.

Claim 11

A spinal needle comprising a hollow outer needle having an outer surface a stylet removably insertable within said hollow outer needle said stylet forward end and said outer needle forward end cooperating in tHe extreme forward position of said stylet to provide a generally closed piercing end said generally closed piercing end having two generally planar side bevel faces and a generally planar heel face said side bevel faces each forming an acute angle with the longitudinal axis of said spinal needle and intersecting one another at an acute angle to form a straight cutting edge inclined to the longitudinal axis of said spinal needle and lying in a plane including the longitudinal axis of said spinal needle said side bevel faces intersecting said outer needle surface to form two curved cutting edges which intesect to form a point, each said side bevel face including a rounded end remote from said point, said heel face being inclined at an angle to the longitudinal axis of said spinal needle and joining said side bevel faces, said heel face having a pointed forward edge joining said straight cutting edge, said closed piercing end having a dimension defined as the distance from said point to the projection of said opposite outer needle surface, measured in a plane containing said straight cutting edge, said cutting edge extending from one-half to three-quarters of said dimension.