The pedunculopontine nucleus, a promising new target for deep brain stimulation in Parkinson's disease, straddles the pontomesencephalic junction--unfamiliar territory to most functional neurosurgeons. This contribution reviews the anatomy of the pedunculopontine and peripeduncular nuclei. Given the reported findings of Mazzone et al. in NeuroReport, the authors postulate that the peripeduncular nucleus might be of previously unexpected clinical relevance.