In mouse models, the femoral nerve primarily innervates the anterior thigh muscles (e.g., quadriceps) and provides sensory innervation to part of the medial leg. However, persistent motor and sensory function after attempted femoral nerve injury could indicate incomplete transection or compensation by other nerves.

Here’s how you can evaluate whether you've created a proper lesion:

1. Anatomical Confirmation

Visual check under magnification: Ensure a clean transection (if that is your intended model) and not just partial crush or contusion. Some researchers mark the injury site with a suture or dye to revisit the same site later.

Use of microsurgical tools: To ensure precision, especially when working with crush or partial transection models.

2. Functional Assessment

Motor function test:

Gait analysis: Use tools like the CatWalk system or simple video-based gait scoring to identify changes in limb usage.

Grasping or paw extension reflex: Loss of quadriceps contraction (knee extension) implies a more complete femoral nerve injury.

Sensory test:Von Frey filaments or hot plate test: These help check cutaneous sensation, though femoral sensory loss may be subtle due to overlap.

3. Electrophysiology

Nerve conduction studies or EMG: Absence or reduction in compound muscle action potentials (CMAPs) from the quadriceps after stimulation of the femoral nerve suggests successful lesioning.

4. Histological Verification

Post-mortem analysis: Staining the injured site with H\&E or neurofilament markers (e.g., NF200) can confirm axonal degeneration or regeneration.

Retrograde labeling: Use of fluorescent tracers injected into the target muscle can confirm if the neuronal connection is disrupted.

5. Consider Other Nerves

Yes, there are other nerves contributing to mouse hindlimb function:

Sciatic nerve: Major contributor to motor and sensory innervation in the posterior thigh and lower leg.

Obturator nerve: Innervates adductor muscles, which might still function even after femoral nerve damage.

Saphenous nerve: Sensory branch of the femoral nerve—if spared, could explain retained sensation.

If motor or sensory function seems too preserved, the sciatic or obturator nerves might be compensating, or the femoral lesion might be incomplete.

The CatWalk system was super useful especially when using the leg extension ratio and ankle angle generated while walking, there were significant differences when verifying this!