Performing Crush Axotomy on the Facial Nerve in a Mouse Model

Begin with an anesthetized mouse placed on its side, with its right ear fixed and the area behind the ear shaved. 

Trace the posterior auricular vein and make a small incision to access underlying tissues. 

Dissect the tissue layers while preventing damage to nearby structures. 

Use a cotton swab to stop any bleeding. 

Locate the white facial nerve. 

Identify the ear canal, a pearly white structure, and the digastric muscle belly as key landmarks for accurately locating the facial nerve.

Dissect around these landmarks to expose the facial nerve trunk containing a bundle of axonal fibers that transmit signals to facial muscles.

Keep the exposed area open and, using forceps, gently crush the facial nerve trunk with constant pressure. 

Repeat the crush at the same site from a perpendicular angle. 

This controlled crushing induces mechanical stress on the axon fibers, resulting in their damage and disruption of neuronal signaling.