Why is having sex and inserting tampons painful for some?

Vaginismus explained

Vaginismus is one of our main areas of focus here at Femina Physical Therapy. Since the founding of Fusion Wellness and Femina PT we have seen great strides being made in the acceptance of a vaginismus diagnosis as something that is not only real, but treatable. So it's good to see a major internet presence like Yahoo! taking note of the subject and spreading the news to a wider audience.

The Yahoo! article defines vaginismus as "the involuntary tightening of the vaginal muscles that makes wanted penetration very painful or even impossible", and it then goes into some depth on some well known causes, myths, and treatments. Here are some snippets from the article interspersed with my own thoughts where needed.

As someone who suffered the debilitating physical and emotional effects of vaginismus (as well as a complicated history of back injuries) for more than 15 years, I thought a "normal" life was just a fantasy. Then I found Heather.