<aside>

The facial nerve (CN VII) is a mixed nerve with motor (facial expression), sensory (taste anterior 2/3 tongue), and parasympathetic (lacrimal/salivary glands) roles.

</aside>

The Facial Nerve (CNVII): Animated Review

https://youtu.be/cejEtT-EtPU

It courses through the temporal bone (facial canal) and parotid gland, making it vulnerable in temporal bone fractures, acoustic schwannomas, parotid tumors, and Bell’s palsy. MRI and CT are key for evaluation of pathology along its course.

General Features

![Anatomy of the cisternal and meatal segments of the facial nerve (cranial nerve [CN] VII). The facial (CN VII) and vestibulocochlear (CN VIII) nerves exit the brainstem at the CPA (cisternal segment) and enter the IAC together. The facial nerve is anterior and superior to the vestibular nerves in the IAC. The orientation of the facial nerve with respect to the superior vestibular nerve (SVN), inferior vestibular nerve (IVN), the cochlear nerve (CN), and the singular nerve (SN) is depicted. Ant. = anterior; GSPN = greater (superficial) petrosal nerve; Inf. = inferior; Pos. = posterior; Sup. = superior; VN = vestibular nerve.

Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/5f7f3604-18ff-4851-86ff-64cec8f8a595/Untitled.png)

Anatomy of the cisternal and meatal segments of the facial nerve (cranial nerve [CN] VII). The facial (CN VII) and vestibulocochlear (CN VIII) nerves exit the brainstem at the CPA (cisternal segment) and enter the IAC together. The facial nerve is anterior and superior to the vestibular nerves in the IAC. The orientation of the facial nerve with respect to the superior vestibular nerve (SVN), inferior vestibular nerve (IVN), the cochlear nerve (CN), and the singular nerve (SN) is depicted. Ant. = anterior; GSPN = greater (superficial) petrosal nerve; Inf. = inferior; Pos. = posterior; Sup. = superior; VN = vestibular nerve.

Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml

![Facial nerve anatomy within the fallopian canal. The course of the facial nerve within the fallopian canal is usually described in 3 anatomical sections that are nearly perpendicular to one another on 3 different 2D planes: the labyrinthine section, the tympanic or horizontal section, and the mastoid or vertical segments. The labyrinthine segment runs laterally above the vestibule, passing between the vestibule and the cochlea until it reaches the medial wall of the middle ear cleft. The tympanic portion runs lateral to the superior semicircular canal, and the mastoid section runs immediately anterior and medial to the lateral semicircular canal.

Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/116811cf-379a-4722-b852-60a1653a98da/Untitled.png)

Facial nerve anatomy within the fallopian canal. The course of the facial nerve within the fallopian canal is usually described in 3 anatomical sections that are nearly perpendicular to one another on 3 different 2D planes: the labyrinthine section, the tympanic or horizontal section, and the mastoid or vertical segments. The labyrinthine segment runs laterally above the vestibule, passing between the vestibule and the cochlea until it reaches the medial wall of the middle ear cleft. The tympanic portion runs lateral to the superior semicircular canal, and the mastoid section runs immediately anterior and medial to the lateral semicircular canal.

Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml

The blood supply of the facial nerve within the temporal bone. Three arteries supply the facial nerve, which are the internal auditory artery (a branch of the anterior inferior cerebellar artery), the petrosal artery (a branch of the middle meningeal artery [MMA]), and the stylomastoid artery (a branch of the posterior auricular artery). a. = artery; ECA = external carotid artery. | Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml

The blood supply of the facial nerve within the temporal bone. Three arteries supply the facial nerve, which are the internal auditory artery (a branch of the anterior inferior cerebellar artery), the petrosal artery (a branch of the middle meningeal artery [MMA]), and the stylomastoid artery (a branch of the posterior auricular artery). a. = artery; ECA = external carotid artery. | Sun, M. Z., Oh, M. C., Safaee, M., Kaur, G., & Parsa, A. T. (2012). Neuroanatomical correlation of the House-Brackmann grading system in the microsurgical treatment of vestibular schwannoma, Neurosurgical Focus FOC, 33(3), E7. Retrieved Aug 28, 2022, from https://thejns.org/focus/view/journals/neurosurg-focus/33/3/2012.6.focus12198.xml

Nuclei (in Pons)

  1. Motor nucleus – muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric.
  2. Nucleus solitarius (rostral part) – taste from anterior 2/3 of tongue.
  3. Superior salivatory nucleus – parasympathetic: lacrimal, submandibular, sublingual glands, nasal/palatal glands.

Normal facial nerve on MRI. (a) Axial CISS image at the level of the pons demonstrates the facial colliculus (arrow) seen as a smallbump along the anterior wall of the fourth ventricle. This is formed by the motor tracts of the facial nerve (purple curved line) coursing aroundthe abducens nucleus (yellow dot). (b) Axial CISS sequence of the left CPA and IAC demonstrates the normal cisternal and intracanalicularsegments of the left CN VII (solid arrow), anterior to CN VIII (double lined arrow).

Normal facial nerve on MRI. (a) Axial CISS image at the level of the pons demonstrates the facial colliculus (arrow) seen as a smallbump along the anterior wall of the fourth ventricle. This is formed by the motor tracts of the facial nerve (purple curved line) coursing aroundthe abducens nucleus (yellow dot). (b) Axial CISS sequence of the left CPA and IAC demonstrates the normal cisternal and intracanalicularsegments of the left CN VII (solid arrow), anterior to CN VIII (double lined arrow).

‌

Course

5 Segments: