Nasion
Pronunciation: NAY-zee-on
The most anterior point of the nasofrontal suture, used as a landmark in cephalometric tracing.
Full Definition
Nasion (N) is the cephalometric landmark located at the most anterior point of the nasofrontal suture, visible in the midsagittal plane on a lateral cephalogram. It serves as a key reference point for constructing planes such as the Sella-Nasion plane and for calculating angular measurements including SNA and SNB. Editors must be aware that 'nasion' refers strictly to the skeletal point, not the soft-tissue equivalent. It is distinct from the soft-tissue nasion (N'), which is used in soft-tissue cephalometric analyses. Correct identification of nasion is foundational to virtually all skeletal classification systems in dentofacial orthopedics.
Usage
Usage note: Always lowercase in running text unless beginning a sentence; abbreviate as 'N' in cephalometric notation.
In Context
- "The clinician identified nasion on the lateral cephalogram before constructing the Sella-Nasion reference plane." — Clinical case report
- "Editors should verify that the author has not conflated nasion with the soft-tissue nasion when reporting angular measurements." — Peer-review checklist