In studies using electrophysiological techniques in the cat and monkey, it was shown that spinal interneurons located in the C3-C4 segments, denoted propriospinal neurons (PNs), and in the same segments as the forelimb motoneurons (FMNs), denoted segmental interneurons (sINs), can mediate disynaptic excitation from motor cortex to FMNs (Alstermark & Lundberg 1992; Alstermark & Isa 2012). In behavioural experiments it was shown that the C3-C4 PNs can mediate the motor command for reaching both in the cat and monkey and for the precision grip between the thumb and index finger in the monkey. In contrast, in the cat the C3-C4 PNs only has a minor contribution to the control of grasping, whereas the sINs can mediate this command. In human, using indirect electrophysiological techniques an analogous system of PNs was demonstrated and it seems that it also contributes to the control of reaching and grasping. In the rodents, much less is known about the role of spinal INs in controlling reaching and grasping. A combination of genetic and cervically-restricted viral labeling (AAV-FLEX) in Chx 10-Cre mice (Azim et al. 2012) revealed that at least 25% of V2a INs do indeed correspond to cervical PNs. Preliminary results suggest that they may control reaching, but not grasping. From a phylogenetic perspective it seems as if the spinal circuits controlling skilled reaching and grasping are conserved, despite differences in connectivity between species. Alstermark, B. & Lundberg, A. 1992. Pergamon Press, 327–354. Alstermark, B. & Isa, T. 2012. Annual Review of Neuroscience 35, online publication. Azim, E., Alstermark, B. & Jessell, T.M. 2012. Society for Neuroscience.