The interspace between the first and second sacral vertebrae (S1/S2) is located at the level of which anatomical landmark?

The interspace between the first and second sacral vertebrae (S1/S2) is anatomically significant for locating various structures during a clinical procedure, such as a lumbar puncture. This interspace corresponds closely with the location of the anterior superior iliac spine (ASIS).

The ASIS serves as a reliable bony landmark, as it resides at the level of the S2 vertebra. This makes it particularly useful for healthcare professionals to identify the appropriate area for administration of injections or accessing the spinal canal. By locating the ASIS, practitioners can then draw an imaginary line horizontally towards the midline and find the S1/S2 interspace.

Understanding this relationship between the ASIS and the sacral vertebrae underscores the importance of anatomical landmarks in medical practice, ensuring both accuracy and safety during procedural interventions.