Obturator Nerve (L2–L4)
The obturator nerve is the primary nerve of the medial compartment of the thigh, responsible for hip adduction.
Anatomy & Innervation
- Course: Originates from the lumbar plexus (L2–L4), travels through the psoas major, descends into the pelvis, and exits through the obturator canal to enter the medial thigh.
- Motor: Innervates the major adductors: Adductor longus, Adductor brevis, Adductor magnus (adductor part), Gracilis, and Obturator externus.
- Sensory: Provides sensation to a small area of the medial aspect of the thigh.
Clinical Significance
| Finding | Description |
|---|---|
| Injury Symptoms | Weakness in hip adduction; sensory deficit on the medial thigh; pain radiating to the medial thigh or knee. |
| Common Causes | Pelvic surgery (e.g., lymph node dissection), pelvic fractures, or compression from large pelvic masses. |
High-Yield Exam Pearl:
Obturator nerve injury can cause pain referred to the medial knee. This is because the obturator nerve provides sensory innervation to the hip and knee joints; clinicians should be cautious not to misattribute medial knee pain solely to local pathology when it may be referred from the hip/pelvis.