A 30-year-old woman presents with low back pain radiating to the posterior calf and lateral foot, with weakness of toe standing on the affected side and absent ankle jerk. The disc herniation is most likely at which level?
- A L3-L4
- B L4-L5
- C L5-S1 ✓
- D L2-L3
Correct answer: C. L5-S1
Explanation
L5-S1 disc herniation compresses the S1 nerve root. S1 supplies the gastrocnemius-soleus (plantarflexion, tested by toe standing), the Achilles tendon reflex, and sensation over the lateral foot and little toe. L4-L5 affects L5 (dorsiflexion, numbness dorsum foot and great toe). L3-L4 affects L4 (knee extension, patellar jerk, medial leg numbness).
Reference: Bailey and Love's Short Practice of Surgery, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.