 Now, here's an interesting example. This is a patient with neurofibromatosis who has an absence phenoid wing. Watch the left eye. It's hard to see here, but that left eye is pulsating back and forth, synchronous with the pulse. And this is because the pulsations occurring centrally are not blocked by the bone between the brain subarachnoid spaces in the orbit. Here it shows up quite dramatically. This is a congenital, bony anomaly that occurs commonly in, for example, neurofibromatosis.