Puncture needle and needle assembly

A needle assembly comprising:

• a hub;
• and
• 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 retained by the 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, an outer diameter of the tapered portion gradually decreasing from a tubular-portion side to a puncture-portion side;
• the puncture portion includes a slit that extends from the distal part of the puncture portion to the hub;
• 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.