The Obex is not synonymous with the upper end of the central canal.
Milhorat
T H
TH
Miller
J I
JI
D002574:Cervical Vertebrae / Q000033:anatomy & histology; D005333:Fetus; D006801:Humans; D013115:Spinal Canal / Q000033:anatomy & histology*; D009626:Terminology as Topic