Why does my arm react when I hit my elbow on the table?

[Celluhh]

um, i placed my elbow on the table, and i think i mustve hit some ideal spot that actually caused a (static?) reaction up my lower arm.

what i want to know is, what exactly it is, why did it happen, and why it only happens sometimes?

 

[Simon Bridge]

Felt like an electric shock right? You hit the nerve in the joint.
You can do it deliberately with a needle and a bit of practice.
It's protected though, which why it hardly ever happens by accident.

 

[Celluhh]

ah i see, thank you!