Hyperacusis following a facial nerve lesion localizes to damage of the nerve to stapedius. At which point does this branch arise from the facial nerve?

• A At the geniculate ganglion
• B At the stylomastoid foramen
• C In the mastoid segment, near the pyramidal eminence ✓
• D Within the internal acoustic meatus

Explanation

The nerve to stapedius arises from the descending (mastoid) segment of the facial nerve close to the pyramidal eminence, just below the second genu, and enters the stapedius muscle. A lesion proximal to this point, such as in the tympanic segment, removes the damping action of stapedius and causes hyperacusis. The chorda tympani also leaves the mastoid segment slightly lower down, so lesions here combine hyperacusis with loss of taste and salivation.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.