What is an innervation ratio?
For each motor axon, there are a variable number of associated muscle fibers. Depending on the specific requirement of control, the ratio may be quite low or extremely high. The innervation ratio of the extraocular muscles is typically 1:3, owing to the fine control required for binocular vision. Conversely, the innervation ratio of the gastrocnemius can be as high as 1:2000 since most movements involving the plantar flexors of the ankle are relatively large motions requiring more force than accuracy.