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 (879 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 large hole at the base of the skull through which the spinal cord passes.
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: Foramen Magnums; Magnum, Foramen; Magnums, Foramen.
Where it fits in the MeSH classification
- Broader topics
- Occipital Bone
Related concepts
Research landscape
PubMed indexes 1,566 records tagged with the MeSH heading “Foramen Magnum” (counts retrieved 2026-10-31). 302 of them (19.3%) were published from 2020 onward, and the busiest period so far is through 1999 with 493 records.
Reviews account for 137 records (8.7%) and meta-analyses for 8. Randomized controlled trials number 4 (0.3%) 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 | 493 |
| 2000-2009 | 291 |
| 2010-2019 | 480 |
| 2020 onward | 302 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 137 | 8.7% |
| Meta-analyses | 8 | 0.5% |
| Randomized controlled trials | 4 | 0.3% |
Method: PubMed query "Foramen Magnum"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
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 |
|---|---|---|---|---|
| Changes in L4/5 Intervertebral Foramen Bony Morphology with Age | 2018 | Research article Design not recorded in structured metadata | 10 | cc by PMID 29769656 · DOI · PMC5955929 |
| A valuable subarachnoid space named the occipito-atlantal cistern | 2023 | Research article Design not recorded in structured metadata | 9 | cc by PMID 37495633 · DOI · PMC10372020 |
| The (extended) achondroplasia foramen magnum score has good observer reliability | 2022 | Research article Design not recorded in structured metadata | 9 | cc by PMID 35396670 · DOI · PMC9271114 |
| Foramen magnum stenosis, cervicomedullary decompression, and growth in children with achondroplasia: a retrospective cohort study | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 41612394 · DOI · PMC12930939 |
Changes in L4/5 Intervertebral Foramen Bony Morphology with Age [1]
Abstract reading summary — source excerpts
- Opening excerpt
- The purpose of this study was to explore the morphological changes in L4/5 intervertebral foramen with age using a digital method.
- Closing excerpt
- This information enhances the knowledge of anatomical changes in intervertebral foramen with age, which provides better understanding of the pathology of intervertebral foramen diseases.
- 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 (178 words)
The purpose of this study was to explore the morphological changes in L4/5 intervertebral foramen with age using a digital method. The closed boundaries of the intervertebral foramen (IGES) in different sagittal slices (inside, middle and outside) were obtained from Mimics, and then imported to a custom-written program, which provided quantitative distance between the nerve root and the closed curves. The quantitative information of each age group was used to produce radar chart and line chart for morphological and statistical analyses. Overall, the intervertebral foramen changes mainly occurred in the inner part from middle age to old age. The foraminal height decreased with age in the inside sagittal slice, while no significant difference was found in the middle sagittal slice or the outside sagittal slice. The foraminal width showed no decrease in each age group or each sagittal plane. The present study described foraminal geometry of asymptomatic males in different sagittal slices with age. This information enhances the knowledge of anatomical changes in intervertebral foramen with age, which provides better understanding of the pathology of intervertebral foramen diseases.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29769656 · DOI · PMC5955929
A valuable subarachnoid space named the occipito-atlantal cistern [2]
Abstract reading summary — source excerpts
- Opening excerpt
- The cisterna magna has been defined as the space between the inferior margin of the cerebellar vermis to the level of the foramen magnum, while an enlarged dorsal subarachnoid space at the occipito-cervical junction extending from the foramen magnum to the upper border of the axis (C2) is still ignored.
- Closing excerpt
- Because of its distinctive anatomy, as well as theoretical and clinical significance, OAC deserves its own name.
- 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 (238 words)
The cisterna magna has been defined as the space between the inferior margin of the cerebellar vermis to the level of the foramen magnum, while an enlarged dorsal subarachnoid space at the occipito-cervical junction extending from the foramen magnum to the upper border of the axis (C2) is still ignored. Recently, the myodural bridge complex is proved to drive the cerebral spinal fluid flowing via this region, we therefore introduce the "occipito-atlantal cistern (OAC)" to better describe the subarachnoid space and provide a detailed rationale. The present study utilized several methods, including MRI, gross anatomical dissection, P45 sheet plastination, and three-dimensional visualization. OAC was observed to be an enlarge subarachnoid space, extending from the foramen magnum to the level of the C2. In the median sagittal plane, OAC was a funnel shape and its anteroposterior dimensions were 15.92 ± 4.20 mm at the level of the C0, 4.49 ± 1.25 mm at the level of the posterior arch of the C1, and 2.88 ± 0.77 mm at the level of the arch of the C2, respectively. In the median sagittal plane, the spino-dural angle of the OAC was calculated to be 35.10 ± 6.91°, and the area of OAC was calculated to be 232.28 ± 71.02 mm2. The present study provides OAC is a subarachnoid space independent from the cisterna magna. Because of its distinctive anatomy, as well as theoretical and clinical significance, OAC deserves its own name.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 37495633 · DOI · PMC10372020
The (extended) achondroplasia foramen magnum score has good observer reliability [3]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundAchondroplasia is the most common skeletal dysplasia.
- Closing excerpt
- Further research is required to prospectively validate the score against clinical outcomes.
- 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 (246 words)
BackgroundAchondroplasia is the most common skeletal dysplasia. A significant complication is foramen magnum stenosis. When severe, compression of the spinal cord may result in sleep apnea, sudden respiratory arrest and death. To avoid complications, surgical decompression of the craniocervical junction is offered in at-risk cases. However, practice varies among centres. To standardize magnetic resonance (MR) reporting, the achondroplasia foramen magnum score was recently developed. The reliability of the score has not been assessed.ObjectiveTo assess the interobserver reliability of the achondroplasia foramen magnum score.Materials and methodsBase of skull imaging of children with achondroplasia under the care of Sheffield Children's Hospital was retrospectively and independently reviewed by four observers using the achondroplasia foramen magnum score. Two-way random-effects intraclass coefficient (ICC) was used to assess inter- and intra-observer reliability.ResultsForty-nine eligible cases and five controls were included. Of these, 10 were scored normal, 17 had a median score of 1 (mild narrowing), 11 had a median score of 2 (effacement of cerebral spinal fluid), 10 had a score of 3 (compression of cord) and 6 had a median score of 4 (cord myelopathic change). Interobserver ICC was 0.72 (95% confidence interval = 0.62-0.81). Intra-observer ICC ranged from 0.60 to 0.86. Reasons for reader disagreement included flow void artefact, subtle T2 cord signal and myelopathic T2 cord change disproportionate to canal narrowing.ConclusionThe achondroplasia foramen magnum score has good interobserver reliability. Imaging features leading to interobserver disagreement have been identified. Further research is required to prospectively validate the score against clinical outcomes.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 35396670 · DOI · PMC9271114
Foramen magnum stenosis, cervicomedullary decompression, and growth in children with achondroplasia: a retrospective cohort study [4]
Abstract reading summary — source excerpts
- Opening excerpt
- BACKGROUND: Foramen magnum stenosis (FMS) is a serious complication in children with achondroplasia that may necessitate cervicomedullary decompression (CMD).
- Closing excerpt
- CONCLUSIONS: Impaired growth in children with foramen magnum stenosis requiring cervicomedullary decompression may primarily reflect greater disease severity, while the potential contribution of surgery remains uncertain.
- 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 (217 words)
BACKGROUND: Foramen magnum stenosis (FMS) is a serious complication in children with achondroplasia that may necessitate cervicomedullary decompression (CMD). It is unclear how FMS and CMD influence growth in these children. This study aimed to assess the effects of FMS and CMD on the growth of children with achondroplasia. METHODS: Eighty-seven children (45 males, 42 females) with achondroplasia, aged 4 to 6 years, were evaluated. Height, weight, head circumference, and body mass index were expressed as standard deviation scores (SDS) according to Merker et al., while sitting height SDS was derived using Tanner’s methods. FMS was graded on magnetic resonance imaging using Fornarino’s score. RESULTS: Fifty-two patients (26 males, 26 females) underwent CMD at a median age of 0.95 years (IQR 0.52;1.50). Of these, 28 (53.8%) were under one year old at the time of CMD, with a median age of 0.6 years (0.4;0.7). The remaining 24 children had CMD after their first year of life, with a median age of 1.6 years (1.3;2.8). The median age at anthropometric assessment was 5.16 years (4.74;5.50). Children who underwent CMD showed significantly lower median height SDS, particularly among males compared to females (p=0.026). CONCLUSIONS: Impaired growth in children with foramen magnum stenosis requiring cervicomedullary decompression may primarily reflect greater disease severity, while the potential contribution of surgery remains uncertain.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41612394 · DOI · PMC12930939
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 The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis [5]
- Research article Foramen magnum meningiomas: detailed surgical approaches and technical aspects at Lariboisière Hospital and review of the literature [6]
- Research article Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation [7]
- Research article Surgery on anterior foramen magnum meningiomas using a conventional posterior suboccipital approach: a report on an experience with 17 cases [8]
- Research article Petroclival and foramen magnum meningiomas: surgical approaches and pitfalls [9]
- Research article Lifetime impact of achondroplasia: Current evidence and perspectives on the natural history [10]
References
- Yan S, Wang K, Zhang Y, Guo S, Zhang Y, Tan J. Changes in L4/5 Intervertebral Foramen Bony Morphology with Age. . 2018. PMID 29769656 · DOI · PMC5955929
- Li YF, Wei RX, Yang KQ, Hack GD, Chi YY, Tang W, et al.. A valuable subarachnoid space named the occipito-atlantal cistern. . 2023. PMID 37495633 · DOI · PMC10372020
- Jenko N, Connolly DJA, Raghavan A, Fernandes JA, Ushewokunze S, Elphick HE, et al.. The (extended) achondroplasia foramen magnum score has good observer reliability. . 2022. PMID 35396670 · DOI · PMC9271114
- Fava D, Angelelli A, Tedesco C, Panciroli M, Bianchin S, Teruzzi D, et al.. Foramen magnum stenosis, cervicomedullary decompression, and growth in children with achondroplasia: a retrospective cohort study. . 2026. PMID 41612394 · DOI · PMC12930939
- Levine DN. The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis. J Neurol Sci. 2004. PMID 15140600 · DOI
- Bruneau M, George B. Foramen magnum meningiomas: detailed surgical approaches and technical aspects at Lariboisière Hospital and review of the literature. Neurosurg Rev. 2008. PMID 17882459 · DOI · PMC2077911
- Hida K, Iwasaki Y, Koyanagi I, Sawamura Y, Abe H. Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation. Neurosurgery. 1995. PMID 8559295 · DOI
- Goel A, Desai K, Muzumdar D. Surgery on anterior foramen magnum meningiomas using a conventional posterior suboccipital approach: a report on an experience with 17 cases. Neurosurgery. 2001. PMID 11440430 · DOI
- Sekhar LN, Wright DC, Richardson R, Monacci W. Petroclival and foramen magnum meningiomas: surgical approaches and pitfalls. J Neurooncol. 1996. PMID 8858531 · DOI
- Hoover-Fong J, Cheung MS, Fano V, Hagenas L, Hecht JT, Ireland P, et al.. Lifetime impact of achondroplasia: Current evidence and perspectives on the natural history. Bone. 2021. PMID 33545406 · 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 2026-10-31.
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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.