For the L4 vertebra, what is the corresponding anatomical landmark?

The correct anatomical landmark corresponding to the L4 vertebra is the iliac crest. The iliac crest is the superior border of the ilium, the largest bone in the pelvis. It typically aligns with the L4 vertebra, making it a useful reference point in clinical practice, especially during procedures involving lumbar punctures or when assessing spinal alignment.

The iliac crest serves as a palpation point that helps practitioners identify the location of the L4 vertebra in relation to the pelvis and lumbar spine. This alignment is important in orthotic and prosthetic fittings and assessments where accurate localization of vertebral levels is necessary.

In contrast, the PSIS (posterior superior iliac spine) is also a landmark but corresponds more closely with the S2 vertebra rather than L4. The xiphoid process and sternal notch are anatomical landmarks associated with the thoracic region and relate more to the upper body structures rather than the lumbar spine, making them irrelevant when discussing the alignment of L4.