An abnormal cervical curve often accompanies a shift in the gravitational line.
I get asked frequently by friends and families if they have a forward head posture. Though I want to give them an answer as simple as yes or no, it’s hard to tell without looking at the X-rays. All I can probably do is make an assumption based on their posture and external look. You should understand that other variables can contribute to having an anterior head carriage such as pelvic tilt.
On a neutral lateral cervical spine film, you can draw a vertical line through the top of the C2 spine perpendicular to the bottom edge of the film. The distance between this line and the anterior and superior corner of the C7 spine can be evaluated. If the line descends anteriorly to this line, it indicates the presence of an anterior gravitational line with a resultant anterior head carriage.
Anterior head carriage is not just a cosmetic issue. It represents where gravitational stresses are acting on your musculoskeletal structure. This would grossly cause anterior weight-bearing posture and is suggestive of an uneven distribution of gravitational forces acting on the discs.
Figure 4.20 (a) Cervical gravitational line (courtesy Don R Leck, BSc, DC, Toronto, Ontario, Canada.) (b) This 47-year-old man demonstrates cervical kyphosis with a 12-mm anterior shift in the gravitational line (courtesy Leo Silvka, DC, FATA, Toronto, Ontario, Canada).