Throughout this bridge, the male voice is transitioning through head voice and thinning to super head voice, which starts on E-flat. This is the third bridge in the male voice. I've only addressed three bridges for men, but theoretically, there can more. If a male singer is able to keep his larynx down and balance the right amount of air against his vocal cords, he could potentially reach a whistle range and have to deal with a few more bridges.
Women's Bridges
Women's bridges take place in a similar fashion as men's: that is, they exist at a distance of about an augmented-fourth interval. They begin, however, where a man's second bridge is. So generally speaking, a woman's first bridge is on an A or B-flat above a keyboard's middle C.

Next is a woman's chest voice range, and above this, up to a D, is mix voice. Once a female vocalist hits an E-flat (or sometimes an E), she is in head voice. Strictly on a technical level, a woman shouldn't sing completely in head voice until an E-flat. (There are stylistic reasons for wanting to find head sooner when you're ascending, but that's another discussion.)

This area of resonation will continue up to an A or B-flat below a keyboard's double-high C. This third bridge puts the female singer in a super head voice, and she will stay in that until she reaches an E-flat above a keyboard's double-high C.

When singing most songs, women don't need to go much past this fourth bridge, but there are a few more bridges beyond this fourth bridge. Once again, they are at intervals of an augmented fourth above the E-flat above a double-high C: the fifth bridge is on A, and the sixth is on the E-flat above that. These last two areas of resonation are known as the whistle range, and as I stated, most women don't use these areas, but they do exist and can be developed.