Image and text used under creative commons licence. Original source: Schwarz ST, Afzal M, Morgan PS et-al. The 'swallow tail' appearance of the healthy nigrosome - a new accurate test of Parkinson's disease: a case-control and retrospective cross-sectional MRI study at 3T. PLoS ONE. 2014;9 (4): e93814. doi:10.1371/journal.pone.0093814