Pars interarticularis

Last revised by Derek Smith on 2 Nov 2023

The pars interarticularis or simply pars (plural: partes interarticulares) is the part of a vertebra located between the superior and inferior articular processes. 

In the axis and the thoracolumbar spine, the pars interarticularis is a narrow isthmus between the superior and inferior facets. In the subaxial cervical spine, the pars interarticularis equivalent is termed the lateral mass or articular pillar.

In the axis, the pars interarticularis is located anterolateral to the spinal canal 5. In the thoracolumbar spine, the pars interarticularis is located posterolateral to the spinal canal.

In the axial plane, the pars is located at the junction of the pedicle and lamina.

In the oblique lumbar radiograph, the neck of the Scottie dog represents the pars.

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