“…Head posture is also a difficult concept to capture in a single quantity. In the literature, different methods have been suggested to do so through measurements made on lateral photographs (Cureton, 1941; Darling et al ., 1984; Braun, 1991; Hackney et al ., 1993; Lee et al ., 1995) or on radiographs (Solow & Tallgren, 1976; Huggare & Raustia, 1992; Visscher et al ., 1998). During the investigations, the participant often attained the so‐called mirror position of the head while standing (Darling et al ., 1984; Huggare & Raustia, 1992; Hackney et al ., 1993; Lee et al ., 1995) or sitting (Braun et al ., 1991; Hackney et al ., 1993).…”