abnormal cerebellar peduncle morphology abnormal middle cerebellar peduncle morphology 2010-02-11T12:50:42Z MP:0009986 MPheno.ontology any structural anomaly of the largest of the three paired cerebellar peduncles; it is composed mainly of afferent fibers that originate within the pontine nuclei as part of the massive corticopontocerebellar tract, whose fibers descend from the sensory and motor areas of the cerebral neocortex, through the pons and into the cerebellar nuclei and cortex csmith