title: Not as simple as it looks.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Barton
mesh_terms: D001917:Brachial Plexus / Q000000981:diagnostic imaging*; D006801:Humans; D009407:Nerve Block / Q000379:methods*; D018084:Ultrasonography, Interventional / Q000379:methods*