Information about Facial Nerve
| Nerve: | ||
|---|---|---|
) | ||
| Cranial nerve VII | ||
| The nerves of the scalp, face, and side of neck. | ||
| Latin | nervus facialis | |
| subject #202 901 | ||
| MeSH | Facial+Nerve | |
| Dorlands/Elsevier | n_05/12565770 | |
Structure
The motor part of the facial nerve arises from the facial nerve nucleus in the pons while the sensory part of the facial nerve arises from the nervus intermedius.The motor part of the facial nerve enters the petrous temporal bone into the internal auditory meatus (intimately close to the inner ear) then runs a tortuous course (including two tight turns) through the facial canal, emerges from the stylomastoid foramen and passes through the parotid gland, where it divides into five major branches. Though it passes through the parotid gland, it does not innervate the gland. This action is the responsibility of cranial nerve IX, the glossopharyngeal nerve.
Inside one of the tight turns in the facial canal, the facial nerve forms the geniculate ganglion.
No other nerve in the body travels such a long distance through a bony canal.
Branches
Inside the facial canal
- Greater petrosal nerve - provides parasympathetic innervation to lacrimal gland, as well as special taste sensory fibers to the palate via the nerve of pterygoid canal.
- Nerve to stapedius - provides motor innervation for stapedius muscle in middle ear
- Chorda tympani - provides parasympathetic innervation to submandibular and sublingual glands and special sensory taste fibers for the anterior 2/3 of the tongue.
Outside skull (distal to stylomastoid foramen)
- Posterior auricular nerve - controls movements of some of the scalp muscles around the ear
- Five major facial branches (in parotid gland) - from top to bottom:
- Temporal branch of the facial nerve
- Zygomatic branch of the facial nerve
- Buccal branch of the facial nerve
- Marginal mandibular branch of the facial nerve
- Cervical branch of the facial nerve
Function
Efferent
Its main function is motor control of most of the muscles of facial expression. It also innervates the posterior belly of the digastric muscle, the stylohyoid muscle, and the stapedius muscle of the middle ear. All of these muscles are striated muscles of branchiomeric origin developing from the 2nd pharyngeal arch.The facial also supplies parasympathetic fibers to the submandibular gland and sublingual glands via chorda tympani and the submandibular ganglion. Parasympathetic innervation serves to increase the flow of saliva from these glands. It also supplies parasympathetic innervation to the nasal mucosa and the lacrimal gland via the pterygopalatine ganglion.
Afferent
In addition, it receives taste sensations from the anterior two-thirds of the tongue and sends them to the nucleus of solitary tract. The facial nerve also supplies a small amount of afferent innervation to the oropharynx above the palatine tonsil. There is also a small amount of cutaneous sensation carried by the nervus intermedius from the skin in and around the auricle (earlobe).Location of Cell Bodies
The cell bodies for the facial nerve are grouped in anatomical areas called nuclei or ganglia. The cell bodies for the afferent nerves are found in the geniculate ganglion for both taste and general afferent sensation. The cell bodies for muscular efferent nerves are found in the facial motor nucleus whereas the cell bodies for the parasympathetic efferent nerves are found in the superior salivatory nucleus.Pathology
People may suffer from acute facial nerve paralysis, which is usually manifested by facial paralysis. Bell's palsy is one type of idiopathic acute facial nerve paralysis, which is more accurately described as a multiple cranial nerve ganglionitis that involves the facial nerve, and most likely results from viral infection and also sometimes as a result of Lyme disease.Testing the facial nerve
Voluntary facial movements, such as wrinkling the brow, showing teeth, frowning, closing the eyes tightly (lagophthalmos)[1] , pursing the lips and puffing out the cheeks, all test the facial nerve. There should be no noticeable asymmetry.In an upper motor neuron lesion, called central seven, only the lower part of the face on the opposite side will be affected, due to the bilateral control to the upper facial muscles.
Lower motor neuron lesions can result in Bell's palsy, manifested as both upper and lower facial weakness on the same side of the lesion.
Taste can be tested on the anterior of the tongue. This can be tested with a swab dipped in a flavoured solution, or with electronic stimulation (similar to putting your tongue on a battery).
Facial nerve can also be tested because it controls about 2/3 of the tongue. Try making your finger moist, and dipping it in some sugar, or salt (something sweet/salty) then touch your finger to the back of your tongue. See if you can taste it!
Additional images
Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries. | Dura mater and its processes exposed by removing part of the right half of the skull, and the brain. | Superficial dissection of brain-stem. Ventral view. | Hind- and mid-brains; postero-lateral view. |
The sphenopalatine ganglion and its branches. | Mandibular division of the trifacial nerve. | Mandibular division of trifacial nerve, seen from the middle line. | ) Plan of the facial and intermediate nerves and their communication with other nerves. |
The course and connections of the facial nerve in the temporal bone. | ) Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ. | View of the inner wall of the tympanum (enlarged.) | The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above. |
) Position of the right bony labyrinth of the ear in the skull, viewed from above. | ) Left temporal bone showing surface markings for the tympanic antrum (red), transverse sinus (blue), and facial nerve (yellow). | Side of neck, showing chief surface markings. | ) Cranial nerves |
) Head facial nerve branches |
References
1. ^ Kliniska Färdigheter: Informationsutbytet Mellan Patient Och Läkare, LINDGREN, STEFAN, ISBN 91-44-37271-X
External links
Latin}}}
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized.
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The pons (sometimes pons Varolii after Costanzo Varolio) is a structure located on the brain stem. It is rostral to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum.
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The medulla oblongata is the lower portion of the brainstem.
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Location
By anatomical terms of location, it is rostral to the spinal cord and caudal to the pons, which is in turn ventral to the cerebellum...... Click the link for more information.
Taste (or more formally, gustation) is a form of direct chemoreception and is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food and poisons.
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The tongue is the large bundle of skeletal muscles on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste. Much of the surface of the tongue is covered in taste buds.
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parasympathetic nervous system (PSNS) is one of three divisions of the autonomic nervous system (ANS). The ANS -a subdivision of the peripheral nervous system (PNS)- is subdivided into the sympathetic (SNS), parasympathetic (PSNS) and enteric (bowels) nervous system (ENS).
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ganglion (pl. ganglia) is a tissue mass, which is composed mainly of somata and dendritic structures, which often interconnect with each other to form a complex system of ganglia known as a plexus.
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The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve (cranial nerve VII). These lower motor neurons innervate the muscles of facial expression and the stapedius.
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The pons (sometimes pons Varolii after Costanzo Varolio) is a structure located on the brain stem. It is rostral to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum.
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The nervus intermedius, or intermediate nerve, is the part of the facial nerve (cranial nerve VII) located between the motor component of the facial nerve and the vestibulocochlear nerve (cranial nerve VIII).
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The temporal bones are situated at the sides and base of the skull.
The temporal bone supports that part of the face known as the temple.
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The temporal bone supports that part of the face known as the temple.
Parts
Each consists of five parts:- Squama temporalis
- Mastoid portion
- Petrous portion
- Tympanic part
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The internal acoustic meatus (also internal auditory meatus) is a canal in the temporal bone of the skull that carries nerves from inside the cranium towards the middle and inner ear compartments.
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The inner ear is the bony labyrinth, a system of passages comprising two main functional parts:
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- the organ of hearing, or cochlea
- and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the vestibule.
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The facial canal is a canal running from the internal acoustic meatus to the stylomastoid foramen. It is also referred to as the aqueduct of Fallopius.
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See also
- facial nerve
- prominence of the facial canal
- hiatus of the facial canal
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stylomastoid foramen
It is the termination of the facial canal, and transmits the facial nerve and stylomastoid artery.
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It is the termination of the facial canal, and transmits the facial nerve and stylomastoid artery.
Clinical Relevance
Bell's palsy can result from inflammation of the facial nerve where it leaves the skull at the stylomastoid foramen...... Click the link for more information.
For the toad wart, see parotoid gland.
The parotid gland is the largest of the salivary glands. It is found wrapped around the mandibular ramus, and it secretes saliva through Stensen's duct into the oral cavity, to facilitate mastication and swallowing.
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The parotid gland is the largest of the salivary glands. It is found wrapped around the mandibular ramus, and it secretes saliva through Stensen's duct into the oral cavity, to facilitate mastication and swallowing.
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The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves. It exits the brainstem out from the sides of the upper medulla, just rostral (closer to the nose) to the vagus nerve.
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The geniculate ganglion (from Latin genu, for "knee") is an L-shaped collection of fibers and sensory neurons of the facial nerve located in the facial canal of the head.
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The greater petrosal nerve is a nerve in the skull that branches from the facial nerve; it forms part of a chain of nerves that innervates the lacrimal gland. The fibres have synapses in the pterygopalatine ganglion.
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The nerve of the pterygoid canal (Vidian nerve), formed by the junction of the great petrosal nerve and the deep petrosal nerve in the cartilaginous substance which fills the foramen lacerum, passes forward, through the pterygoid canal, with the corresponding artery (artery
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The Nerve to the Stapedius (tympanic branch) arises opposite the pyramidal eminence.
It passes through a small canal in this eminence to reach the muscle.
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It passes through a small canal in this eminence to reach the muscle.
External links
- nerve+to+stapedius+muscle at eMedicine Dictionary
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The stapedius is the smallest striated muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes.
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The chorda tympani is a nerve that branches from the facial nerve (cranial nerve VII) inside the facial canal, just before the facial nerve exits the skull via the stylomastoid foramen.
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stylomastoid foramen
It is the termination of the facial canal, and transmits the facial nerve and stylomastoid artery.
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It is the termination of the facial canal, and transmits the facial nerve and stylomastoid artery.
Clinical Relevance
Bell's palsy can result from inflammation of the facial nerve where it leaves the skull at the stylomastoid foramen...... Click the link for more information.
The Posterior Auricular Nerve arises close to the stylo-mastoid foramen, and runs upward in front of the mastoid process; here it is joined by a filament from the auricular branch of the vagus, and communicates with the posterior branch of the great auricular, and with the lesser
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The Temporal branches of the facial nerve cross the zygomatic arch to the temporal region, supplying the Auriculares anterior and superior, and joining with the zygomaticotemporal branch of the maxillary, and with the auriculotemporal branch of the mandibular.
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The Zygomatic branches of the facial nerve (malar branches) run across the zygomatic bone to the lateral angle of the orbit, where they supply the Orbicularis oculi, and join with filaments from the lacrimal nerve and the zygomaticofacial branch of the maxillary nerve.
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