A 55-year-old man presents with low back pain radiating to the anterior thigh and medial leg, with weakness of knee extension and a diminished knee jerk. The most likely level of disc herniation is:
- A L3-L4 ✓
- B L2-L3
- C L4-L5
- D L5-S1
Correct answer: A. L3-L4
Explanation
L3-L4 disc herniation compresses the L4 nerve root. L4 supplies the quadriceps (knee extension), the patellar tendon reflex, and sensation over the anterior thigh and medial leg. L4-L5 affects L5 (dorsiflexion weakness, numbness dorsum of foot). L5-S1 affects S1 (plantarflexion weakness, absent ankle jerk). L2-L3 would affect hip flexion and the upper anterior thigh.
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.