Muscle spindles are multi-functional.

The number and distribution of mammalian muscle spindles in their parent muscle are not simply related to overall muscle length because (i) they lie in parallel to muscle-fibers in series to elastic elements; (ii) muscle architectures are complex and may be functionally partitioned; (iii) task-dependent fusimotor inputs co-determine spindle firing and (iv) the complex central connectivity co-determines the functional use made of spindle afferent signals. Muscle spindles are multi-functional.