SET T0013 -
Emergency Department

• Normal lateral radiograph.
• Most injuries in the cervical spine affect the upper end - C1 and C2; and the lower end - C5, C6, and C7.
• It follows that the two most useful views in a cervical spine series are: (1) the long lateral radiograph - it shows both the upper end and the lower end; and (2) the open mouth peg view - it demonstrates the lateral masses of C1 & C2 . . . and, importantly, whether the alignment of those lateral masses is within normal limits.

See : Accident & Emergency Radiology : A Survival Guide (3rd edition) : Pages 172-173

(1) We have provided you with the top of the long lateral only.

• The C1/C2 articulation is anatomically normal.
• If you have trouble in understanding the normal anatomical alignments, we advise that you start by identifying the anterior arch of the C1 vertebra. Positionally this shadow is a constant on all lateral radiographs. Sometimes referred to as the " D " shadow. Alternatively, we have given it the nickname of the " Coffee Bean " shadow . . .

See : Accident & Emergency Radiology : A Survival Guide (3rd edition) : Pages 174-175

(2) This open mouth peg view is anatomically normal.

• The peg is unremarkable. It does not lean; it is not bent. Remember the aphorism : " A bent peg is a bad peg ".
• The lateral masses of C1 and C2 align . . .

See : Accident & Emergency Radiology : A Survival Guide (3rd edition) : Pages 180, 186-187

This view is normal.

The lateral masses align.

The peg is not bent.

The transverse line crossing the base of the peg is a Mach effect. It is not a fracture.

Mach effect ???  . . .

See : Accident & Emergency Radiology : A Survival Guide (3rd edition) : Page 183

 Normal appearances.

• The odontoid peg is not bent. It does not lean.
• The vertical line crossing the peg is not a fracture. It is the air gap between the incisors.
• Agreed, the lateral masses on the patient's right side do not align precisely, but they do align on the patient's left side.

 A word or two regarding the alignment of the lateral masses on the open mouth AP peg view :

• Their alignment must be assessed - always.
• Sometimes the lateral masses on one side do not align precisely. This can be due to either: (a) rotation of the patient's neck, or (b) developmental hypoplasia of a lateral mass. The latter is not uncommon.

See : Accident & Emergency Radiology : A Survival Guide (3rd edition) : Pages 186-187,191