The muscle attachments of the forearm act to predict displacement of radius fractures. A. The supinator muscle supinates, the bicep muscle flexes, and the pronator teres and pronator quadratus muscles pronate. A fracture of the proximal radius at location 1 will result in a supinated and flexed proximal fragment and a pronated distal fragment. When the fracture is distal to the pronator teres insertion at location 2, the proximal fragment will be neutral and flexed while the distal fragment is pronated and pulled toward the ulna. B. The brachioradialis and abductor pollicis longus muscles act to pull distal fragments more proximally, resulting in overriding fragments. Source: Forearm, Simon’s Emergency Orthopedics, 7e Citation: Sherman SC. Simon’s Emergency Orthopedics, 7e; 2014 Available at: http://accessemergencymedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/1132/p9780071819657-ch013_f003.png&sec=64415846&BookID=1132&ChapterSecID=64415838&imagename= Accessed: October 24, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved