Labyrinthine segment of facial nerve

The labyrinthine segment of facial nerve (F3) begins after the facial nerve has passed through the fundus of internal acoustic meatus in the facial area. After the internal acoustic meatus, the motor root of the facial nerve and the nervus intermedius enter the facial canal (Fallopian Canal), and they then pass between the cochlea and vestibule before bending posteriorly at the geniculate ganglion, at which point the motor root and nervus intermedius join.

The labyrinthine segment gives off two branches:

• The greater superficial petrosal nerve (containing parasympathetic fibers for the lacrimal gland and taste fibers from the palate)

• The external petrosal nerve (not listed in terminologia anatomica)