Review Question - QID 214137

A 33-year-old male presents to the office with low back pain radiating down his right leg. He reports the pain has gotten worse over the last several weeks. He is fairly active and plays pick-up basketball at his local gym 3 times per week. He takes an anti-inflammatory daily which provides mild relief of his symptoms. On physical exam, he has weakness with right great toe extension and relatively tight hamstrings. With straight leg raise he does have moderate discomfort in his low back bilaterally. His pedal pulses are palpable and he has a normal adult hair pattern on his bilateral lower extremities. Which of the following pathologies is most likely to be causing his symptoms?