Step 1 : Introduction to the question "What is the "chelidon"?"
...Everyone knows where their elbows are but few realize the opposite side of the elbow also has a name: the chelidon. This is the spot where the nurse places the stethoscope while measuring your blood pressure. This is where the EMT will feel for a brachial pulse. Because large superficial veins run through this area, it is an ideal sport for a phlebotomist or physician to draw blood. As anyone who has ever banged their elbow knows, there's a couple of large nerves crossing through this area of the arm, too. Source: Reference.com