Professional and Linguistic Assessments Board (PLAB) Practice Exam

At which level does the iliac crest typically lie in the spine?

1. L4

2. L2

3. L5

4. S1

The correct answer is: L4

The iliac crest typically lies at the level of the fourth lumbar vertebra (L4). This anatomical landmark is useful for various clinical applications, including spinal anesthesia and the identification of lumbar puncture sites. When examining the human body in a standing position, the iliac crest, which is the superior border of the ilium of the pelvis, is easily palpable, and placing it in line with L4 helps healthcare professionals visualize the relationship between the pelvis and the lumbar spine. This positioning is particularly relevant when assessing spinal alignment or planning interventions. Understanding this landmark in relation to the spinal column is essential for medical practitioners, as it provides insight into both the anatomy and pathology of the lumbar region. The lumbar vertebrae are numbered L1 through L5, with L4 being an important reference point.