Out of these two techniques which will do generally more damage to an opponent? My understanding is that since the nerves are more exposed in the calf it takes fewer calf kicks to cripple the leg, but are there other considerations as well? Is one better than the other in certain situations and if so how.
Kicks to the calf aren't generally going to do as much damage as kicks to the thigh. That's because of two reasons: 1) The thigh is less mobile. And 2) The thigh has more mass and is a bigger target.
Most trained fighters will lift up their leg when they see a kick coming to their calf. It's quick and easy to do. But it's not easy to get out of the way of a thigh kick.
Even if you don't lift up your leg in defense of a calf kick, if the kick has a lot of force behind it, what will generally happen is your leg will get pushed to the side. You'll become unbalanced as a result, but your calf will be fine.
The only times a calf kick can really do much damage to the calf itself is if that foot is pinned to the ground with all the person's weight over it so that the leg can't slide out of the way. In that case, kicks to the calf can result in broken bones. It's very rare to see in martial arts. It's much more likely that the leg will simply be swept instead of broken. Stomp kicks might work better than round kicks would, but the angle you'd need to have makes it very difficult in practice.
Hope that helps.
Adding my two cents to very good Steve's answer.
Some additional points for being thigh kicks more dangerous:
- calf can be (and usually is) conditioned much better, than thigh.
- hitting thigh with your shin is generally better, because your shin is obviously more solid - here you are hitting-soft-with-hardness
- hitting thigh injures your opponent's muscles nearly directly. Some such hits may "weigh" leg considerably
Calf kicks would be effective if there would be a huge gap in leg conditioning between you and your opponent. Then, yes - you would definitely hit his leg out with calf kicks rather quickly.
Adding to mentioned above, there is some other way to not block, but absorb some damage from thigh kicks. If you don't have time to lift up your leg, try to turn your leg under hit more frontally, towards hit - to prevent your leg being hit from the side - which is more painful and more dengerous for you.