Will contraction of a muscle occur if the upper motor neurons serving it have been destroyed?

Answer 1

The muscle should be constantly be contracting, because the upper motor neurons inhibit teh contraction...loss of umns lead to symptoms of spasms, loss of volutary control, etc.

Answer 2

The muscle will be in a state of tetany - constant contraction - because the UMN is inhibitory in its function. Without the action of the UMN, the muscle will constantly contract. This is seen in Cerebral Palsy.

Answer 3

In this case the only way a skeletal muscle will contract is to use an artifical muscle stimulator.