The facial nerve follows a complex path from the brainstem to the face.
Facial Nerve Pathway Explained
The facial nerve (CN VII) controls facial expressions, taste from the anterior two-thirds of the tongue, and supplies some glands in the head and neck. It has a long and winding pathway that makes it vulnerable to injury at several points. According to the provided reference, its pathway begins at the pons.
Here's a breakdown of its course:
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Origin at the Pons: The facial nerve emerges from the brainstem (specifically, the pons) as two separate roots.
- A motor root, known as the facial nerve proper. This primarily controls the muscles of facial expression.
- A combined sensory and autonomic root, known as the intermediate nerve (nervus intermedius). This carries taste sensations from the anterior two-thirds of the tongue and provides parasympathetic innervation to the lacrimal (tear) gland, submandibular gland, and sublingual gland.
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Cerebellopontine Angle (CPA): The two roots travel together through the cerebellopontine angle, a space between the cerebellum and the pons.
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Internal Auditory Meatus (IAM): The nerve then enters the temporal bone through the internal auditory meatus (also called the internal auditory canal). This canal also carries the vestibulocochlear nerve (CN VIII).
