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Topographical Landmarks Used in Radiographic Positioning

Topographical Landmarks

1. Acanthion – midline junction of the upper lip and auricle nose.
2. Auricle or Pinna – ear or outer ear.
3. External Acoustic Meatus – external opening into the ear cannal.
4. Glabella – smooth triangular area, superior to the bridge of the nose and between the eyebrows.
5. Gonion – lower posterior angle seen on each side of the jaw or mandible.
6. Infraorbital Margin or IOM – inferior rim of the orbital base.
7. Inion – prominent bump midline at the back of the head. It is also known as ”external occipital protuberance”.
8. Inner Canthus – junction of the upper and lower eyelids.
9. Mental point – midpoint of the chin. It is in the center of the flat triangular region.
10. Mentum – a flat triangular region.
11. Nasion – slight depression at the bridge of the nose and it marks the junction of the frontal and nasal lobes.
12. Superciliary ridge – a.k.a superciliary arch. It is the ridge of the bone found over each eye and under each eyebrow.
13. Tragus – small flack of cartilage over the EAM.
14. Vertex – most superior portion of the head.


The author is a Radiologic Technologist, currently in the academic field, hoping to mold and produce future Radiologic Technologists who will be theoretically and technologically competent.

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