Median sensory tracing Median sensory tracing. Sensory nerve conduction study of the median nerve. The median sensory nerve action potential (SNAP) is displayed on the top 2 lines, and in this case the bottom 2 lines display the ulnar SNAP. Numerical data pertaining to the SNAP responses is displayed on the right. Source: EMG and Nerve Conduction Studies, Atlas of Pain Medicine Procedures Citation: Diwan S, Staats PS. Atlas of Pain Medicine Procedures; 2015 Available at: http://accessanesthesiology.mhmedical.com/DownloadImage.aspx?image=/data/Books/1158/diw_ch12_f012.png&sec=78933656&BookID=1158&ChapterSecID=64176251&imagename= Accessed: September 22, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved