The intracranial part of the facial nerve leaves the posterior cranial fossa through the internal acoustic meatus and traverses the temporal bone. At which anatomical point does the facial nerve finally exit the skull?

• A Foramen ovale
• B Stylomastoid foramen ✓
• C Mastoid emissary foramen
• D Petrotympic (Glaserian) fissure

Explanation

After its intratemporal course through the labyrinthine, tympanic and mastoid segments of the facial canal, the facial nerve exits the temporal bone at the stylomastoid foramen between the styloid and mastoid processes. It then enters the parotid gland and divides into its five terminal branches. The petrotympanic fissure transmits the chorda tympani out of the middle ear, not the main trunk, which is what kills option D.

Reference: Gray's Anatomy for Students, 4th ed.

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