Stellate ganglion block targets are C6 transverse process or C7 transverse process in anterior paratracheal approach which is most popular method. Cricoid cartilage is known that it is located at C6 level in supine neutral position of the neck. But stellate ganglion block is performed in supine extended position of the neck. So cricoid cartilage will move up to cephalad direction and pain doctors should find C6 or C7 transverse process at lower neck area than cricoid cartilage.

Inclusion Criteria:

• adults above age of 20 reserved for musculoskeletal ultrasonography

Exclusion Criteria:

1. past history of neck surgery
2. the limitation of neck motion due to rheumatoid arthritis, et al.
3. severe neck pain
4. inability to communicate or read or write