Pars interarticularis

Overview
The pars interarticularis is the part of the vertebra located between the inferior and superior articular processes of the facet joint.

Anatomy
In the transverse plane, it lies between the lamina and pedicle. It is abnormal in spondylolysis, either due to fracture or congenitally.

Pathophysiology
It is abnormal in spondylolysis, either due to fracture or congenitally.

Imaging
On an anterior oblique radiograph of the lumbar spine, the pars is the neck of the imaginary Scottie dog; the Scottie dog's eye is the pedicle, its hindlegs the spinous process, its nose the transverse process and its forelegs the inferior articular facet.