Pars interarticularis

The pars interarticularis, or pars for short, is the part of vertebra located between the inferior and superior articular processes of the facet joint.

In the transverse plane, it lies between the lamina and pedicle. In other words, in the axial view, it is the bony mass between the facets that is anterior to the lamina and posterior to the pedicle. It is abnormal in spondylolysis, either due to fracture or congenitally. Bilateral C2 pars fractures are known as the hangman's fracture.