Atlanto-occipital assimilation
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View Henry Knipe's current disclosuresAt the time the article was last revised Ryan Thibodeau had no financial relationships to ineligible companies to disclose.
View Ryan Thibodeau's current disclosures- Atlantooccipital fusion
- Atlanto-occipital fusion
- Occipitalization
- Occipitalisation
- Fusion between atlas and axis
Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae.
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Epidemiology
Atlanto-occipital assimilation occurs in approximately 0.5% (range 0.08-3%) of the population 2-5. It is thought to affect males and females equally.
Associations
Atlanto-occipital assimilation is associated with 2:
fusion of C2 and C3 (occurs in 50% of cases)
basilar invagination: type 1
Clinical presentation
It is typically asymptomatic but symptoms from nerve or vascular compression can occur.
Pathology
Fusion of C1 to the occiput can be either 3:
complete: C1 not identifiable
incomplete: C1 partially identifiable
It can also be classified as
posterior arch assimilation
anterior arch assimilation
assimilation of both the anterior and posterior arches
Quiz questions
References
- 1. Smoker W. Craniovertebral Junction: Normal Anatomy, Craniometry, and Congenital Anomalies. Radiographics. 1994;14(2):255-77. doi:10.1148/radiographics.14.2.8190952 - Pubmed
- 2. Arthur C. Aufderheide, Conrado Rodriguez-Martin. The Cambridge Encyclopedia of Human Paleopathology. (1998) ISBN: 9780521552035 - Google Books
- 3. Jrgen Freyschmidt, Joachim Brossmann. Koehler/Zimmer's Borderlands of Normal and Early Pathological Findings in Skeletal Radiography. (2011) ISBN: 9783131606358 - Google Books
- 4. Electricwala A, Harsule A, Chavan V, Electricwala J. Complete Atlantooccipital Assimilation with Basilar Invagination and Atlantoaxial Subluxation Treated Non-Surgically: A Case Report. Cureus. 2017;9(6):e1327. doi:10.7759/cureus.1327 - Pubmed
- 5. Ferreira E & Botelho R. Atlas Assimilation Patterns in Different Types of Adult Craniocervical Junction Malformations. Spine (Phila Pa 1976). 2015;40(22):1763-8. doi:10.1097/BRS.0000000000001045 - Pubmed
Incoming Links
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- Atlanto-occipital assimilation
Related articles: Anatomy: Spine
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osteology
- vertebrae
- spinal canal
- cervical spine
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- lumbar spine
- sacrum
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anatomical variants
- vertebral body
- neural arch
- transitional vertebrae
- ossicles
- ossification centers
- intervertebral disc
- articulations
- ligaments
- musculature of the vertebral column
- muscles of the neck
- muscles of the back
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suboccipital muscle group
- rectus capitis posterior major muscle
- rectus capitis posterior minor muscle
- obliquus capitis superior muscle
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- quadratus lumborum muscle
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suboccipital muscle group
- spinal meninges and spaces
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spinal cord
- gross anatomy
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white matter tracts (white matter)
- corticospinal tract
- anterolateral columns
- lateral columns
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dorsal columns
- fasiculus gracilis (column of Goll)
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