We discussed the anatomy and the developmental alterations of a neuronal circuit, already implied in the pathogenesis of the palatal myoclonus, and connecting the dentate nucleus in the cerebellum with the red nucleus and the inferior olivary nucleus in the brainstem, in the context of our findings obtained in a wide set of sudden intrauterine unexplained death (SIUD) and sudden infant death syndrome (SIDS). We observed high incidence of developmental alterations (hypoplasia, hyperplasia, and high c-fos neuronal immunopositivity) of the three nuclei in both SIDS and SIUD, frequently associated to serotonergic abnormalities and to maternal smoking in pregnancy. We underlined the likeness of these neurological abnormalities with the neuropathologic picture marking the palatal myoclonus. We concluded that the network connecting the dentate, the red, and the inferior olivary nuclei is involved in the pathogenesis of a wide spectrum of manifestations, which, even if quite different, can be ascribed to a defective muscular contraction, frequently triggered from hypoxic conditions. Wrong contraction of eye, face, and throat muscles can lead to palatal myoclonus; wrong contracture of the upper airway muscles can be involved in the pathogenetic mechanism of the sudden fetal death and sudden infant death in the first months of life.