Martha uses this when she helpfully points out parts of my body that are too fat, or do I have this confused?

I can't understand why people keep looking for corresponding body parts when the parts they need are right there. Why accept substitutes - just start out with the part in question.

The correlation of the workings of completely unrelated body parts. Reminds me of when Freud diagnosed a female patient's repeated nosebleeds as a sign of her latent sexual desire for him.

Pure quackery. Basically, the concept is that each part of the body is represented by a corresponding part of the iris of the eye, and examination of said iris is a valuable diagnostic tool for both preventive and reactive medicine. The ancestors of the modern practitioners sold snake oil.