The portion of the body known as the "Adam's Apple" is actually the frontal surface of the Larynx, or voicebox, which contains the human vocal chords. The Larynx itself is an expansion of the Trachea (windpipe,) is semi-bony, and rigid to the touch.
The reason it is more visible in the male (as a rule) has to do with the amount and distribution of subcutaneous fat. The average body fat content for a male runs around 15-18%, and is usually distributed in the hands, feet, and to a lesset extent, legs and torso. (It is interesting to note that there is little to no muscle in the hands and feet - this is why bodybuilders appear to have hands that are too small for them. The muscles that operated the hands and fingers are in the forearm, and the muscles for the feet are in the calves.)
In females, body fat averages 25-30% - this is where they get all those wonderful curves, and why they also have a much easier time floating in water than men. Female subcutaneous fat is more evenly distributed thruout the torso, from the neck down thru the hips. The structure of the hands and feet is similar - it is the extra 10% or so that gives the body curves.
Of course, there are individual variances in body fat amounts and distribution. Bodybuilders of either gender with the "cut" or "ripped" look are typically under 5% body fat - sometimes down to 2%.
The name "Adam's Apple" derives from the Biblical tale of the Garden of Eden. It is meant to be G-d's mark on Man for listening to the woman (who was, in turn, decieved by the serpent.) Man is twice decieved, and therefore marked.
Better now?
FFZ
Warrior, philosopher, and purveyor of obscure information.