Obturator nerve innervates all of the following muscles except
**Core Concept**
The obturator nerve is a branch of the lumbar plexus, primarily responsible for innervating the adductor muscles of the thigh, which are crucial for hip adduction. The obturator nerve is formed by the union of the anterior and posterior divisions of the lumbar plexus and exits the pelvis through the obturator foramen.
**Why the Correct Answer is Right**
The obturator nerve innervates the adductor longus, adductor brevis, adductor magnus (adductor part), and gracilis muscles. These muscles work together to facilitate hip adduction, which is essential for various movements like walking, running, and maintaining balance. The obturator nerve also innervates the obturator externus muscle, which assists in hip flexion and external rotation.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the obturator nerve does innervate the adductor longus muscle.
**Option B:** Incorrect because the obturator nerve does innervate the adductor brevis muscle.
**Option C:** Incorrect because the obturator nerve does innervate the adductor magnus (adductor part) muscle.
**Option D:** Incorrect because the obturator nerve does innervate the gracilis muscle.
**Clinical Pearl / High-Yield Fact**
When examining a patient with femoral nerve injury, it is essential to note that the obturator nerve is spared, allowing for the normal functioning of the adductor muscles.
**Correct Answer:** D. Obturator nerve does not innervate the quadriceps femoris muscle.