From: The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study
C0C1
C1C2
C2C3
C3C4
C4C5
C5C6
C6C7
Flexion
17.7
19.4
15.6
12.8
20.4
18.6
18.3
Extension
26.7
21.2
14.6
18.0
17.8
16.3