Is viewing pictures of women's nakedness in medical textbooks for study and learning purposes forbidden, and is practicing masturbation out of fear for one's health forbidden?

It is forbidden to look at the-private-parts of a man or a woman without necessity or urgent need, whether in a book or on a screen. A doctor or a student of knowledge is permitted to look only at the area of need. As for masturbation, it is forbidden, but if a person is between two choices, either fornication or masturbation, then masturbation is the lesser of two evils.