Purpose Anatomic variations complicate surface landmark-guided needle placement, thereby increasing nerve blockade failure rate. and 25.3??8.0?mm, respectively, in the extended supine position. In the extended supine position, the cricoid cartilage was more cephalad than C6TP and C7TP in all patients. The distance from the cricoid cartilage to C6TP was 12.1??7.6?mm in men and 17.2??7.7?mm in women. Conclusion C6TP and C7TP are located approximately 15 and 25?mm, respectively, caudal to the cricoid cartilage in the extended supine position. Our results spotlight the fact that there can be significant anatomic variation between the extended and neutral supine positions used in stellate ganglion block, which should be kept in mind when devising easily identifiable and palpable surface landmarks. test was used to compare differences between buy 488-81-3 the extended and neutral positions. The two-sample test was used to compare differences by sex. A value <0.05 was considered to be statistically significant. Statistical Package for the Social Sciences version 20.0 software (IBM Corp., Armonk, NY, USA) was used Rabbit polyclonal to ZNF484. for all statistical analyses. Results Forty-two patients (16 men, 26 women; mean age 54.5?years; range 27C91?years) were included in the study. Demographic data buy 488-81-3 for the participants are shown in Table?1. Table?1 Demographic data of the patients In the neutral supine position, the mean distances from the cricoid cartilage to buy 488-81-3 the C6TP and C7TP were 6.0 and 15.1?mm, respectively. In the extended supine position, these distances were 15.2 and 25.3?mm, respectively. The difference between the corresponding distances in the neutral and extended supine positions was statistically significant (p?p?=?0.028) and extended (p?=?0.041) supine positions. The distance from the cricoid cartilage to the C6TP was significantly different between the neutral and extended supine positions in both sexes (p?p?=?0.148) or in the extended supine position (p?=?0.132); however, it was different between the two positions in both men (p?p?