Measurements
The investigator instructed participants to identify the CTM using an anatomical chart of the neck. First, students were taught either of the techniques. The participants were then directed to palpate their own CTM and to imagine the structure. However, as we did not allow them to touch other person’s CTM, they did no practice identifying the CTM before the examination. This didactic training took approximately 15 min.Immediately after the lecture, the students took turns in attempting to identify the CTM of the investigator, a male in his ages 35–40 years old with a body mass index (BMI) of 35 kg/mThe procedure involved participants standing with their hands down on the left side of the subject, who lay in a neutral supine position on a bed. When the team member timing the procedure gave a verbal cue to start, the participants began the manoeuvre. When the participant declared ‘I found’, the timing was stopped. The students kept their fingers at the site, and then they marked the point with a permanent marker which they identified as the CTM site. After that, the accuracy of the location was assessed by another investigator (an eighth-year attending ED physician) using ultrasound (Noblus, Hitachi Medical Corporation, Tokyo, Japan) with the longitudinal technique [After all the participants had completed procedures, they took a 10-minute break, and then the other manoeuvre was lectured and performed in the same way.