Einthoven's Quadrilateral
From Gomerpedia
After the creation of Einthoven's triangle, Willem Einthoven thought he would try his luck with other shapes, resulting in Einthoven's quadrilateral. This was a huge fail. "Abysmal" is a common word used by cardiologists to describe Einthoven's quadrilateral. It is even worse than Einthoven's pentagon.
Confusion
Einthoven's quadrilateral is a completely different entity from Einthoven's quadriceps, which are simply Einthoven's front thigh muscles.