3 Must go together? MaQianZi + TianXianZi + TianNanXing

Hi,

I'm trying to work out the purpose of a combination of three herbs in a Shaolin medicine used for injury pain relief.

Nux Vomica + Henbane + Arisaematis Heterophylli

I was thinking maybe anti-inflammatory and pain relief, but I cannot find a lot of research in English which explains why these three in particular where chosen by the Shaolin for this formula.

It is clear that they seem to go together, as they counteract each other's side-effects.

Nux Vomica excites the nervous system, and can cause convulsions in case of overdose.

Henbane (Semina Hyoscyami) is an anti-spasmodic

Arisaematis Heterophylli is an anti-convulsive.

They all seem to have analgesic properties.  Nux Vomica is anti-inflammatory (that's been documented.)

But, the thing is, there are lots of other herbs which the Shaolin could have used for this purpose, so why did they chose these three?

What is unique about this combination?  Any ideas?

I don't pretend to be an expert in this, so if I've made any mistakes, please let me know!  But I hope that, eventually, I'll get there...