Thank you all for erudite and interesting comments.

This is why this is SUCH a good Xray to discuss.  Those who criticised the 
image are quite right - it isn't a very good image, and is inadequate in 
the technical sense as it does not show all the cervical spine. But that 
is real; that is what we have to cope with day in, day out. As I pointed 
out, the original picture is rather better - but I was careful not to 
damage what I perceived as the abnormalities.

My question was only - is this a normal Xray? 

I believe there are three abnormalities; two easy to see and in my view 
incontrovertible and one difficult to see and arguable.

The first and to my eye most obvious abnormality is the posterior step if 
you run your eye down the vertebral bodies. Look at the magnified images 
of the C4/5 region on http://www.emergencyunit.com/images/close.htm.

You will see that if you run your eye down the front of the vertebral 
bodies they are in alignment. However, if you look down the BACK, there is 
a step at C4/5. Definite, no argument. That should lead you to look  at 
the curvature of the lines once more back at 
http://www.emergencyunit.com/images/cspine.jpg. 

Remember, in a young fit person artificial lines running down front and 
back of the bodies should curve gently and smoothly. Look again at the 
front of the vertebral bodies, and you will see a quite clear smooth line 
- to C4/5 when you will see a change and a second sinuous line down to the 
haze at C7. It is like a sail constrained by rigging.

The third abnormality I see is that there is something awry with the facet 
joints. Again, looking at the closeup, I think that there is a 
discontinuity which represents a unifacetal fracture and that this film 
demonstrates a displacement. I have tried to outline this on the right 
side film. Furthermore, this insignificant little lesion 
is unstable.

I'm not sure if there is an associated soft-tissue abnormality as Jean has 
suggested, as this is the difficult zone where the laryngeal 
apparatus starts. He may very well be right.

I'm not saying my interpretation is right. I have looked at an awful lot 
of cervical spine films and I am prepared to defend my opinion. What I 
will say is that I have DELIBERATELY not yet reviewed his CT scans, 
although I am told that he has a unifacet fracture dislocation which had 
to be fixed.

I think this is a fabulous film. It has demonstrated that a very ordinary 
film which many eminent and skilled colleagues of mine have stated is 
normal can hide a significant abnormality to the expert as well as the 
tyro. It also demonstrates that a structured and pedantic review of the 
film ATLS style does spot the problem. 

As Tim Coats has said, the very fact I have invited comment means that I 
think it is abnormal and this will have swayed everyone's judgement in 
this forum. Many people fixed on the dens because it was difficult to see 
- but the real abnormalities are plain to see, I contend. More than that, 
there is a lesson here. In the event of an altered sensorium (in the 
wonderful speak of ATLS) fail to CT the neck and the whole neck at your 
peril.

Now, a further question. How would you deal with a junior who missed this 
abnormality?

/Rowley./