Measurement · JACB
Anterior cranial base (N–S) — Jarabak
Loading the reference ceph.
Definition
The anterior cranial base length, Sella to Nasion, as the upper-anterior limb of the Björk polygon.
How
Measure N→S in mm.
Purpose
In the Jarabak set the linear limbs let you compare face parts against the cranial base: mandibular body length is expected to roughly match anterior cranial base length (1:1) by maturity.
High
Above the norm reads as a long anterior cranial base — expect a correspondingly long mandibular body.
Low
Below the norm reads as a short anterior cranial base — a 'normal' body length is actually relatively long.
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so Anterior cranial base (N–S) — Jarabak here is a real reading and not a diagram.