The odontoid or 'peg' projection, also known as the open mouth AP projection (or radiograph), is an AP projection of C1 (atlas) and C2 (axis) with the patient's mouth open. This view focuses primarily on the odontoid process of C2, and is useful in visualizing odontoid and Jefferson fractures.

The odontoid or 'peg' projection is an AP projection of C1 (atlas) and C2 (axis). This view focuses primarily on the odontoid process, and is useful in visualizing odontoid and Jefferson fractures. patient’s shoulders should be at equal distances from the image receptor to avoid rotation, the head facing straight forward.

The first cervical vertebra is called the atlas. It articulates with the skull base above and the second vertebra of the cervical spine or axis below. The open-mouth (odontoid) view visualizes the atlanto-axial complex, primarily the odontoid process (dens) and the lateral masses of C1 in relation to the body and articular pillars of C2.

The standard Fuchs view (Figure 1 and 3) should not be used in a trauma setting and the modified Fuchs view (Figure 2) may be used instead. The entire odontoid process should be visibly to avoid obscuring anatomy. More likely to avoid structures overlapping the odontoid than with the open mouth odontoid view.