Notes on Facial Nerve

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FACIAL NERVE

Type:

Mixed motory and sensory (N. intermedius) (general visceral efferent, general somatic afferent, special visceral afferent and efferent).

Roots:

1. Motor component.

2. Sensory component (N. intermedius).

Course of Nerve:

Internal acoustic meatus, petrous part of temporal bone, facial canal (geniculate ganglion) and exits the skull via the stylomastoid foramen. Within the parotid gland splits into two main divisions:

a. Temporo-facial division.

b. Cervico-facial division.

Terminates in 5 peripheral branches (temporal, zygomatic, buccal, mandibular, and cervical.

Supplies:

Muscles of facial expression, scalp and auricle muscles, buccinator, platysma, stapedius, stylohyoid muscle and posterior digastric belly. Special sensory supply anterior two-thirds of tongue (taste fibres via chorda tympani nerve), soft palate taste fibres (via palatine and greater petrosal nerves and secretomotor parasympathetic fibres to the submandibular, sublingual, and lacrimal glands and glands of the nasal and palatine mucosa.

Nuclei:

1. Facial motor nucleus (PONS).

2. Nucleus solitarius (medulla - sensory taste fibres).

3. Geniculate ganglion (sensory).

Branches:

Within Facial Canal:

1. Greater (superficial) petrosal nerve - contains N. intermedius fibres - taste fibres.

2. Communicating (with lesser superficial petrosal nerve) and deep petrosal nerve (sympathetic fibres around the internal carotid artery) to form the nerve of the pterygoid canal that enters the pterygopalatine ganglion.

3. External petrosal.

4. Nerve to stapedius (dampens auditory signal).

5. Chorda tympani (passes in inner ear between handle of malleus and long process of the incus. Supplies anterior two-thirds of the tongue with taste fibres and secreto-motor fibres (via the submandibular ganglion) to the submandibular, sublingual and buccal glands (parasympathetic). Taste fibres are carried by the lingual nerve to the tongue.

At Exit from Stylo-mastoid foramen:

1. Posterior auricular (supplies auricularis posterior and posterior belly of occipito-frontalis).

2. Stylo-hyoid.

3. Digastric (posterior belly).

On Face via Parotid Plexus:

1. Temporal.

2. Zygomatic.

3. Buccal.

4. Mandibular.

5. Cervical.

Nervus Intermedius:

Often termed sensory root of the facial nerve.

Origin:

Secretomotor and sensory.

1. Secretomotor (para-sympathetic): floor of mouth, lacrimal gland, palate, nasal cavity, nasopharynx and paranasal sinuses.

2. Sensory (taste): cell bodies in the facial geniculate ganglion; nucleus tractus solitarius.

Branches:

1. Greater (superficial) petrosal nerve (secreto-motor to palate and taste fibres on the oral surface of the palate). Joined by deep petrosal nerve to form the nerve of the pterygoid canal which enters the pterygo-palatine ganglion.

2. Tympanic branches.

3. Chorda tympani (secreto-motor for the glands in the floor of the mouth and taste anterior two-thirds of tongue.

Further Topics on Cranial Nerves:

1. Introduction to Cranial Nerves
2. Notes on Olfactory Nerve CN 1
3. Notes on Optic Nerve CN 2
4. Notes on Oculomotor Nerve CN 3
5. Notes on Trochlear Nerve CN 4
6. Notes on Trigeminal Nerve CN 5
7. Notes on Abducens Nerve CN 6
8. Notes on Facial Nerve CN 7
9. Notes on Vestibulocochlear Nerve CN 8
10. Notes on Glossopharyngeal Nerve CN 9
11. Notes on Vagus Nerve CN 10
12. Notes on Accessory Nerve CN 11
13. Notes on Hypoglossal Nerve CN 12
14. Summary of Cranial Nerve Nuclei
15. Summary of Cranial Nerve Functions

Additional Reading:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures
23. What is a Cough Reflex?
24. Notes on Congenital Prosopagnosia
25. Findings in Parkinson's Disease
26. Types of Heat Strokes
27. Types of Strokes
28. What is Benign Intracranial Hypertension?
29. What is Cauda Equina Syndrome?
30. Cranial Nerve Locations in Brain Stem

Neurology Videos

1. Video of Neurology Examination in a Clinical Setting

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

Related Topics

1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

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