Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (718 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The 7th cranial nerve. The facial nerve has two parts, the larger motor root which may be called the facial nerve proper, and the smaller intermediate or sensory root. Together they provide efferent innervation to the muscles of facial expression and to the lacrimal and salivary glands, and convey afferent information for taste from the anterior two-thirds of the tongue and for touch from the external ear.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Facial Nerves; Nerve, Facial; Seventh Cranial Nerve; Cranial Nerve, Seventh; Nerve, Seventh Cranial; Seventh Cranial Nerves; Cranial Nerve VII; Cranial Nerve VIIs.
Where it fits in the MeSH classification
- Broader topics
- Autonomic Pathways; Parasympathetic Nervous System; Cranial Nerves
- Narrower topics
- Chorda Tympani Nerve; Geniculate Ganglion
- See also
- Facial Nucleus
Related concepts
- Salivary Glands
- Taste
- Tongue
- Touch
- External Ear
Research landscape
PubMed indexes 12,834 records tagged with the MeSH heading “Facial Nerve” (counts retrieved 2026-10-29). 1,705 of them (13.3%) were published from 2020 onward, and the busiest period so far is through 1999 with 6,791 records.
Reviews account for 918 records (7.2%) and meta-analyses for 56. Randomized controlled trials number 81 (0.6%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 6,791 |
| 2000-2009 | 2,082 |
| 2010-2019 | 2,256 |
| 2020 onward | 1,705 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 918 | 7.2% |
| Meta-analyses | 56 | 0.4% |
| Randomized controlled trials | 81 | 0.6% |
Method: PubMed query "Facial Nerve"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in neuroscience
Neuroscience draws on tools with different strengths: cellular and animal work can manipulate circuits directly, while human imaging and electrophysiology observe the living brain at lower resolution. Small imaging studies are prone to false positives, and findings in animals do not always carry over to people. Clinical neurology and psychiatry rely on trials and cohort studies whose outcomes are often symptom scales. Check the species, the sample size, how the outcome was measured and whether results were replicated.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Breadth of tuning in taste afferent neurons varies with stimulus strength | 2015 | Research article Design not recorded in structured metadata | 85 | cc by PMID 26373451 · DOI · PMC4573454 |
| Transcriptomes and neurotransmitter profiles of classes of gustatory and somatosensory neurons in the geniculate ganglion | 2017 | Research article Design not recorded in structured metadata | 61 | cc by PMID 28970527 · DOI · PMC5624912 |
| Hemifacial spasm and neurovascular compression | 2014 | Review article Design not recorded in structured metadata | 59 | cc by PMID 25405219 · DOI · PMC4227371 |
| Nerve Injury-Induced Immune Responses in the Taste Bud Target Field | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 41751976 · DOI · PMC12940848 |
Breadth of tuning in taste afferent neurons varies with stimulus strength [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Gustatory stimuli are detected by taste buds and transmitted to the hindbrain via sensory afferent neurons.
- Closing excerpt
- Altogether, our data suggest that taste is encoded by activity in patterns of peripheral sensory neurons and challenge the notion of strict labelled line coding.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (152 words)
Gustatory stimuli are detected by taste buds and transmitted to the hindbrain via sensory afferent neurons. Whether each taste quality (sweet, bitter and so on) is encoded by separate neurons ('labelled lines') remains controversial. We used mice expressing GCaMP3 in geniculate ganglion sensory neurons to investigate taste-evoked activity. Using confocal calcium imaging, we recorded responses to oral stimulation with prototypic taste stimuli. Up to 69% of neurons respond to multiple tastants. Moreover, neurons tuned to a single taste quality at low concentration become more broadly tuned when stimuli are presented at higher concentration. Responses to sucrose and monosodium glutamate are most related. Although mice prefer dilute NaCl solutions and avoid concentrated NaCl, we found no evidence for two separate populations of sensory neurons that encode this distinction. Altogether, our data suggest that taste is encoded by activity in patterns of peripheral sensory neurons and challenge the notion of strict labelled line coding.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 26373451 · DOI · PMC4573454
Transcriptomes and neurotransmitter profiles of classes of gustatory and somatosensory neurons in the geniculate ganglion [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Taste buds are innervated by neurons whose cell bodies reside in cranial sensory ganglia.
- Closing excerpt
- Here, the authors report single cell RNA sequencing and unbiased transcriptome analyses to reveal major distinctions between gustatory and somatosensory neurons and subclusters of gustatory neurons with unique molecular and functional profiles.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (194 words)
Taste buds are innervated by neurons whose cell bodies reside in cranial sensory ganglia. Studies on the functional properties and connectivity of these neurons are hindered by the lack of markers to define their molecular identities and classes. The mouse geniculate ganglion contains chemosensory neurons innervating lingual and palatal taste buds and somatosensory neurons innervating the pinna. Here, we report single cell RNA sequencing of geniculate ganglion neurons. Using unbiased transcriptome analyses, we show a pronounced separation between two major clusters which, by anterograde labeling, correspond to gustatory and somatosensory neurons. Among the gustatory neurons, three subclusters are present, each with its own complement of transcription factors and neurotransmitter response profiles. The smallest subcluster expresses both gustatory- and mechanosensory-related genes, suggesting a novel type of sensory neuron. We identify several markers to help dissect the functional distinctions among gustatory neurons and address questions regarding target interactions and taste coding.Characterization of gustatory neural pathways has suffered due to a lack of molecular markers. Here, the authors report single cell RNA sequencing and unbiased transcriptome analyses to reveal major distinctions between gustatory and somatosensory neurons and subclusters of gustatory neurons with unique molecular and functional profiles.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 28970527 · DOI · PMC5624912
Hemifacial spasm and neurovascular compression [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck.
- Closing excerpt
- With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (197 words)
Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck. Its prevalence is 9.8 per 100,000 persons with an average age of onset of 44 years. The accepted pathophysiology of HFS suggests that it is a disease process of the nerve root entry zone of the facial nerve. HFS can be divided into two types: primary and secondary. Primary HFS is triggered by vascular compression whereas secondary HFS comprises all other causes of facial nerve damage. Clinical examination and imaging modalities such as electromyography (EMG) and magnetic resonance imaging (MRI) are useful to differentiate HFS from other facial movement disorders and for intraoperative planning. The standard medical management for HFS is botulinum neurotoxin (BoNT) injections, which provides low-risk but limited symptomatic relief. The only curative treatment for HFS is microvascular decompression (MVD), a surgical intervention that provides lasting symptomatic relief by reducing compression of the facial nerve root. With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 25405219 · DOI · PMC4227371
Nerve Injury-Induced Immune Responses in the Taste Bud Target Field [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Damage to the chorda tympani (CT) nerve through trauma or experimental nerve axotomy results in the degeneration of anterior taste buds and taste loss.
- Closing excerpt
- The presence of pro-regenerative M2-like macrophages may play a role in later taste bud regeneration and functional recovery in the injured peripheral taste system.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (175 words)
Damage to the chorda tympani (CT) nerve through trauma or experimental nerve axotomy results in the degeneration of anterior taste buds and taste loss. Our previous work demonstrated that interleukin-1 receptor 1 (Il1r) signaling is required for taste bud regeneration and the recovery of taste function. However, the effects of experimental axotomy on immune responses in the absence of Il1r signaling remain unclear. Here we performed unilateral CT sectioning in Il1r KO or wild-type mice to observe changes in innate immune cell populations in the anterior taste field. We found that CD45+ immune cells, CD68+ and CD206+ M2-like macrophages are significantly increased near anterior taste buds at days two and five post-injury in wild-type but not Il1r KO mice. However, taste buds degenerated at similar time points in both strains, suggesting that a suppressed immune responses in the absence of Il1r signaling is not the primary reason for later functional deficits. The presence of pro-regenerative M2-like macrophages may play a role in later taste bud regeneration and functional recovery in the injured peripheral taste system.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41751976 · DOI · PMC12940848
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Facial nerve grading instruments: systematic review of the literature and suggestion for uniformity [5]
- Research article Management of peripheral facial nerve palsy [6]
- Research article Electrophysiology of the facial nerve in hemifacial spasm: ectopic/ephaptic excitation [7]
- Research article The organization of taste sensibilities in hamster chorda tympani nerve fibers [8]
- Research article Neural mechanisms of facial sensation [9]
- Research article Facial nerve preservation after vestibular schwannoma Gamma Knife radiosurgery [10]
References
- Wu A, Dvoryanchikov G, Pereira E, Chaudhari N, Roper SD. Breadth of tuning in taste afferent neurons varies with stimulus strength. . 2015. PMID 26373451 · DOI · PMC4573454
- Dvoryanchikov G, Hernandez D, Roebber JK, Hill DL, Roper SD, Chaudhari N. Transcriptomes and neurotransmitter profiles of classes of gustatory and somatosensory neurons in the geniculate ganglion. . 2017. PMID 28970527 · DOI · PMC5624912
- Lu AY, Yeung JT, Gerrard JL, Michaelides EM, Sekula RF, Bulsara KR. Hemifacial spasm and neurovascular compression. . 2014. PMID 25405219 · DOI · PMC4227371
- Brown J, Bao Y, Ali T, Heisey E, Ogala O, Hardeman T, et al.. Nerve Injury-Induced Immune Responses in the Taste Bud Target Field. . 2026. PMID 41751976 · DOI · PMC12940848
- Fattah AY, Gurusinghe ADR, Gavilan J, Hadlock TA, Marcus JR, Marres H, et al.. Facial nerve grading instruments: systematic review of the literature and suggestion for uniformity. Plast Reconstr Surg. 2015. PMID 25357164 · DOI
- Finsterer J. Management of peripheral facial nerve palsy. Eur Arch Otorhinolaryngol. 2008. PMID 18368417 · DOI · PMC2440925
- Nielsen VK. Electrophysiology of the facial nerve in hemifacial spasm: ectopic/ephaptic excitation. Muscle Nerve. 1985. PMID 2995804 · DOI
- Frank ME, Bieber SL, Smith DV. The organization of taste sensibilities in hamster chorda tympani nerve fibers. J Gen Physiol. 1988. PMID 3047313 · DOI · PMC2217629
- Darian-Smith I. Neural mechanisms of facial sensation. Int Rev Neurobiol. 1966. PMID 5337728 · DOI
- Yang I, Sughrue ME, Han SJ, Fang S, Aranda D, Cheung SW, et al.. Facial nerve preservation after vestibular schwannoma Gamma Knife radiosurgery. J Neurooncol. 2009. PMID 19430881 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-29.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.