Homunculus of Touch

Argh. Been feeling kind of defeated lately with these frustrating qbank questions. Overall I'm improving somewhat, but my scores are erratic - they spike up and then plummet and then spike again. Anyway, after studying neurology for the better part of a day, I managed to pull off a 71% on a block of neuro questions! Not sure how that happened, as I generally consider neuro to be one of my weaker areas.

Somewhat related, one of the most interesting things I remembered learning while going through neuro was the somatosensory homunculus. You see, sensation is unevenly distributed throughout our bodies and our brains form a somatosensory homunculus of it on the pre-frontal cortex. It's rather interesting. So think, what are the most sensitive parts of your body? Now look at the distribution of the somatosensory cortex:

Does it match what you thought? You'll notice that the face and hands are far over-represented. The fingers, lips, and face are more sensitive than pretty much any other part of the body. Do you notice the genitals? Hint: it's by the feet. Interesting that it comprises such a small part of the homunculus. A drawing of the somatosensory homunculus would be like this:

So I find it kind of funny how we put so much focus and attention on the penis and genitals. Yeah, sure, it's pretty sensitive given its body surface area (more so than, say, the legs), but it pales in comparison to the hands, lips, and face. One would probably expected the homunculus to be more like this:

Lol, right? Well, apparently, some recent-ish studies kind of hint that the homunculus actually is a bit more like this last version (the things you find on Google, lol). In 2005, Kell et al. attempted to update the somatosensory homunculus for males - chiefly that genital sensation is not near the feet in the somatosensory cortex, but closer to where it'd be on the body. In 2007, Sorrells et al. reported that 5 of the most sensitive parts of the penis is removed during circumcision (so it's curious, and incorrect, that the homunculus above is circumcised).

Of course, one has to wonder, what about women? It's been presumed that the number of genital nerve endings in men and women are about equal; however, there just aren't that many such studies out there done on women. There are numbers floating around in the internet (with no source that I can pin down) stating that the glans clitoris (basically the entire clitoris) has about 8000 nerve endings, whereas the glans penis (head of the penis) has about 4000; presumably, the other 4000 nerve endings are distributed along the shaft. Furthermore, the foreskin has about 10,000 to 20,000 nerve endings (and the clitoral hood somewhere around there but perhaps a little less).

What does all this mean? Who knows. Everyone experiences sensation different anyhow. Sure, there are objective ways to test sensation: 2-point discrimination, temperature, fine touch, coarse touch, vibration, etc. And there are different nerves that sense different things (apparently the foreskin has a bunch of the kind that detect fine touch and vibration). But what it all "means" is another thing entirely. I mean, though the hands are sensitive, they're not particularly sensual, am I right?

Anywho, I'm rambling. I hope you were entertained and curiosity piqued. :-P