Diaphragm (optics) curved blades improve the roundness of the iris opening. In a photograph, the number of blades that the iris diaphragm has can be guessed by counting the number of diffraction spikes converging from a light source or bright reflection. For an odd number of blades, there are twice as many spikes as there are blades. In case of an even number of blades, the two spikes per blade will overlap each other, so the number of spikes visible will be the number of blades in the diaphragm used. This is most apparent in pictures taken in the dark with small
Superior fascia of the urogenital diaphragm Superior fascia of the urogenital diaphragm The superior fascia of the urogenital diaphragm is continuous with the obturator fascia and stretches across the pubic arch. If the obturator fascia be traced medially after leaving the Obturator internus muscle, it will be found attached by some of its deeper or anterior fibers to the inner margin of the pubic arch, while its superficial or posterior fibers pass over this attachment to become continuous with the superior fascia of the urogenital diaphragm. Behind, this layer of the fascia is continuous with the inferior fascia and with the fascia of Colles; in front