Space
Facial canal
The bony course of the facial nerve
High-yield
Follow three segments: labyrinthine, tympanic and mastoid. The narrow labyrinthine passage and its relatively sparse vascular connections can make a swollen nerve vulnerable to compression.
Overview
After entering the internal acoustic meatus, CN VII follows a bent passage through the temporal bone. The labyrinthine segment reaches the geniculate ganglion. The tympanic segment then passes posteriorly above the oval window and below the lateral semicircular canal. A second bend leads into the descending mastoid segment and ultimately the stylomastoid foramen.
Reference facts
- Boundaries
- A temporal-bone canal from the fundus of the internal acoustic meatus to the stylomastoid foramen
- Contents
- CN VII with its sensory and parasympathetic components, the geniculate ganglion, accompanying vessels, and branch origins including the greater petrosal nerve, stapedius nerve and chorda tympani
- Communications
- Connects with the internal acoustic meatus and stylomastoid foramen; branch canaliculi lead toward the middle ear and greater-petrosal hiatus. The canal is not normally freely open along the middle-ear cavity
Clinical correlation
Associated deficits help estimate where facial-nerve injury occurred: reduced tearing may involve the greater petrosal pathway, sound intolerance the stapedius branch, and altered anterior-tongue taste the chorda tympani. These functions and anatomical variation make localization approximate rather than certain.
Frequently asked questions
What are the boundaries of the facial canal?
A temporal-bone canal from the fundus of the internal acoustic meatus to the stylomastoid foramen.
What does the facial canal contain?
CN VII with its sensory and parasympathetic components, the geniculate ganglion, accompanying vessels, and branch origins including the greater petrosal nerve, stapedius nerve and chorda tympani.
What does the facial canal communicate with?
Connects with the internal acoustic meatus and stylomastoid foramen; branch canaliculi lead toward the middle ear and greater-petrosal hiatus. The canal is not normally freely open along the middle-ear cavity.