Foramen magnum
Last revised by Tariq Walizai
on 5 Jul 2024
Citation, DOI, disclosures and article data
Citation:
Maingard J, Walizai T, Smith D, et al. Foramen magnum. Reference article, Radiopaedia.org (Accessed on 15 Jan 2025) https://doi.org/10.53347/rID-25317
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rID:
25317
Article created:
19 Oct 2013,
Julian Maingard ◈
Disclosures:
At the time the article was created Julian Maingard had no recorded disclosures.
View Julian Maingard's current disclosures
Last revised:
5 Jul 2024,
Tariq Walizai
Disclosures:
At the time the article was last revised Tariq Walizai had no financial relationships to ineligible companies to disclose.
View Tariq Walizai's current disclosures
Revisions:
11 times, by
9 contributors -
see full revision history and disclosures
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The foramen magnum is the largest foramen of the skull and is part of the occipital bone 1. It is oval in shape with a large anteroposterior diameter 2.
On this page:
Gross anatomy
The foramen magnum is found in the most inferior part of the posterior cranial fossa 3. It is traversed by vital structures including the medulla oblongata 1. In the midline, the anterior margin is the basion and the posterior margin is the opisthion.
Relations
anteriorly: basilar part of occipital bone
anterolaterally: occipital condyles, hypoglossal canal, jugular foramen
posteriorly: squamous part of occipital bone with the internal occipital crest
Contents
spinal root of the accessory nerve
Radiographic features
CT
at the level of the foramen magnum CSF is seen to surround the medulla which is reduced or absent in tonsillar herniation
Related pathology
foramen magnum meningioma 2
Quiz questions
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References
- 1. Avci E, Dagtekin A, Ozturk AH et-al. Anatomical variations of the foramen magnum, occipital condyle and jugular tubercle. Turk Neurosurg. 2010;21 (2): 181-90. doi:10.5137/1019-5149.JTN.3838-10.1 - Pubmed citation
- 2. Boulton MR, Cusimano MD. Foramen magnum meningiomas: concepts, classifications, and nuances. Neurosurg Focus. 2006;14 (6): e10. Pubmed citation
- 3. Drake. Gray's Basic Anatomy: with STUDENT CONSULT Online Access, 1e (Grays Anatomy for Students). Churchill Livingstone. ISBN:1455710784. Read it at Google Books - Find it at Amazon
Incoming Links
Articles:
- Head ultrasound
- Clivus
- Dura mater
- Opisthion
- Spinal pia mater
- Marginal sinus (foramen magnum)
- Posterior atlanto-occipital membrane
- Cerebellar tonsillar position
- CSF flow studies
- Chiari 1.5 malformation
- Achondroplasia
- Spinal arachnoid mater
- McRae line
- Occipital sinus
- Cisterna magna
- Cervical spine ligaments
- Craniocervical fixation
- Blunt cerebrovascular injury
- Cerebellum
- Obex
Cases:
- Basilar invagination
- Chiari 1 malformation with syrinx
- Cerebellopontine angle epidermoid cyst
- Intracranial neurenteric cyst
- Chiari I malformation with syrinx
- Chiari I with syrinx and skull base anomalies
- Chiari I malformation with syrinx
- Chiari 1.5 malformation
- Chiari II malformation - subependymal heterotopia - absent septum pellucidum
- Medulloblastoma - SHH subgroup
- Epidermoid cyst - posterior cranial fossa
- Cerebellar abscess
- Alobar holoprosencephaly
- Chiari I malformation with syrinx
- Pituitary stalk interruption syndrome and Chiari I malformation
- Chiari II malformation - fetal MRI
- Neurofibromatosis type 2
- Leptomeningeal drop metastases - medulloblastoma
- Proatlantal intersegmental artery
- Foramen magnum meningioma
Multiple choice questions:
Related articles: Anatomy: Head and neck
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cranial vault
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sutures
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- frontozygomatic suture
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common carotid artery
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arterial supply
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trigeminal nerve (CN V) (mnemonic)
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