Table 1: lines predicting the inferior limit of the EEA to CCJ
Study/Year of publication	Type	Line ^§	Starting point	End point	Line extension	Comments
De Almedia et al 2009	17 patients	Nasopalatine line (NPL)	Rhinion*	Most posterior point on the hard palate	Posteriorly and inferiorly until its intersection with the vertebral column	Overestimates the inferior limit
Baird et al 2009	Nine cadaveric specimens	-	Rhinion	Within 3 to 5 mm from the base of the surgical resection	-	Performed on normal cadavers
Aldana et al 2011	Six cadaver specimens	Superior nostril-hard palate line (SN-HP Line)	Superior aspect of the nostril	Anterior border of C1-C2 junction	-	Performed on normal cadavers, underestimates the inferior limit
Aldana et al 2012	Nine cadaver specimens	Naso-axial line (NAxL)	Midpoint of the distance from rhinion to the anterior nasal spine of the maxillary bone	Tip of the posterior nasal spine of palatine bone	Posteriorly and inferiorly until its intersection with the vertebral column	Performed on normal cadavers, overestimates the lower limits
La Corte et al 2015	Six patients (4 adult and 2 pediatric)	Rhinopalatine Line (RPL)	The two-thirds point of the distance from the rhinion to the anterior nasal spine of the maxillary bone	Posterior nasal spine of the palatine bone	Posteriorly and inferiorly until its intersection with the vertebral column
* The most inferior point on the nasal bone § All lines were taken in the mid sagittal plane of a computed tomography (CT) scan