Puncture needle and needle assembly

A puncture needle comprising:

• a puncture portion comprising:
• a distal part comprising a blade surface, and
• a proximal part having a substantially constant outer diameter;
• and
• a retained portion connected to the proximal part of the puncture portion and configured to be retained by a hub;
• wherein:
• the retained portion comprises:
• a tubular portion having a substantially constant outer diameter larger than a maximum outer diameter of the proximal part of the puncture portion, and
• a tapered portion located between the proximal part of the puncture portion and the tubular portion;
• the puncture portion includes a slit that extends from the distal part of the puncture portion to the tapered portion of the retained portion;
• in the tapered portion, in a top view with the slit facing upward, an outermost diameter of the puncture needle gradually increases from a puncture portion side to a tubular portion side, while a width of the slit gradually decreases from the puncture portion side to the tubular portion side;
• and
• in a lateral view with the slit facing upward, lower contour lines of the puncture portion, the tubular portion, and the tapered portion are collinear.