Problem:

My cat was licking my arm with his sandpaper like tongue. It hurt and the area he was licking was slightly smarting afterwards. However, when he licks the palm of my hand the feeling is rather ticklish and results in no pain during or after.

We can pick up sharp, prickly, abrasive objects with our hands (palms/fingers) and even rub against them and have little to no damage incurred. However, if we do the same with say the back of our hand we are more likely to be injured.

I thought maybe the skin is thicker in our palms and that is resulting in our palms being more resilient. But, our palms are so sensitive to touch that it makes me think the skin is thinner to allow the nerves closer access to our environment.

Required:

Question: Why is there such a stark difference in different areas of skin on our body when it comes to feeling pain and being susceptible to injury from scrapes, bruises, cuts, etc?

Any help would be greatly appreciated!