Spondylolysis is identified by a defect in which part of the vertebra?

Spondylolysis is a specific condition characterized by a defect in the pars inter-articularis of the vertebra. The pars inter-articularis is a narrow region of bone that connects the superior and inferior articular processes of the vertebra, located between the facets. This area is particularly susceptible to stress fractures, often due to repetitive hyperextension activities, such as those seen in athletes or individuals involved in certain sports. The defect can lead to instability of the vertebral segment and is often identified through imaging studies, such as X-rays or MRI.

Understanding this, the other options refer to different anatomical parts of the vertebra. The spinous process is a bony projection on the posterior aspect that serves as an attachment point for muscles and ligaments, while the transverse process also provides sites for muscle and ligament attachments along the sides of the vertebra. The vertebral body is the main weight-bearing part of the vertebra. However, none of these structures are involved in the defect associated with spondylolysis, making the pars inter-articularis the correct and relevant choice for this condition.