Related Experiment Video

Updated: Feb 8, 2026

3D Printing Model of a Patient's Specific Lumbar Vertebra

3D Printing Model of a Patient's Specific Lumbar Vertebra

Published on: April 14, 2023

Prevalence of anatomic variations of the atlas vertebra

Juan A Sanchis-Gimeno¹, Susanna Llido¹, Marcelino Perez-Bermejo²

¹Department of Anatomy and Human Embryology, Faculty of Medicine, University of Valencia, Avda Blasco Ibanez 15, E46010 Valencia, Spain.

The Spine Journal : Official Journal of the North American Spine Society

|July 1, 2018

Abstract

Background Context:

The retrotransverse foramen (RTF), arcuate foramen (AF), unclosed transverse foramen (UTF) and posterior atlas arch defects (PAAD) are anatomic variations of the atlas vertebra that surgeons must be aware of before spine surgery is performed.

Purpose:

To analyze the prevalence of the AF, RTF, UTF, and PAAD.

Study Design:

Ex-vivo anatomical study.

Patient Sample:

Two hundred eighteen atlas vertebrae obtained from 100 Caucasian subjects and 118 sub-Saharan African subjects (48 Sotho subjects, 35 Xhosa subjects and 35 Zulu subjects).

Methods:

We studied 218 atlas vertebrae from skeletons of the Raymond A. Dart Collection in order to analyze the prevalence of AF, RTF, UTF, and PAAD in both Caucasian and sub-Saharan African subjects.

Outcome Measures:

Not applicable.

Results:

Sixty-nine (31.2%) atlases presented anatomical variants: 64 (29.3%) presented one anatomical variant, 4 (1.8%) presented two, and 1 (0.5%) presented three. AF, RTF, UTF, Type A and Type E defects were present in 35 (16.1%), 17 (7.8%), 17 (7.8%), 5 (2.3%), and 1 (0.5%) vertebrae, respectively. The vertebrae with two anatomical variants presented a bilateral UTF and a Type A defect, a bilateral AF and a Type A defect, a right UTF and a left AF, and a right UTF and a Type E defect. The vertebra with three anatomical variants presented a bilateral RTF, a left UTF, and a left AF. No sex differences in prevalence of the RTF (p=.775), AF (p=.605), UTF (p=.408) and Type A defects (p=1.000) were found in the sub-Saharan African and Caucasian groups (RTF, p=.306; AF, p=.346; UTF, p=.121; Type A defects, p=.561). Comparison between the sub-Saharan African (all subjects) and the Caucasian group revealed no differences in the UTF (p=.105), AF (p=.144), RTF (p=.542) and Type A defects (p=.521) prevalence. Also, no differences in the prevalence of the UTF (p=.515), AF (p=.278), and RTF (p=.857) between Zulu, Xhosa and Sotho subjects were found. Neither were found sex differences in the prevalence of UTF, RTF and AF in Zulu (p=.805, p=.234, p=.129), Xhosa (p=.269, p=.181, p=.309), and Sotho subjects (p=.062, p=.590, p=.106).

Conclusions:

The present study has revealed no sex differences in the prevalence of AF, UTF, RTF or PAAD in both Caucasian and sub-Saharan African subjects. This research has also indicated no differences in the prevalence of the UTF, AF and RTF between Zulu, Xhosa and Sotho subjects. In addition, this study has revealed no differences in the Type A, UTF, AF, and RTF prevalence between the sub-Saharan African (all subjects) and the Caucasian subjects. These variations may be known by surgeons before spine surgery for better planning.

Keywords:

Anatomic variations Arcuate foramen Atlas Posterior atlas arch defects Retrotransverse foramen Spine Unclosed transverse foramen

More Related Videos

Author Spotlight: Enhancing Small Animal Bone Compression Testing for Research

Author Spotlight: Enhancing Small Animal Bone Compression Testing for Research

Published on: December 1, 2023

Whole-brain Segmentation and Change-point Analysis of Anatomical Brain MRI—Application in Premanifest Huntington's Disease

Whole-brain Segmentation and Change-point Analysis of Anatomical Brain MRI—Application in Premanifest Huntington's Disease

Published on: June 9, 2018

Related Concept Videos

Prevalence and Incidence

Prevalence and Incidence

In statistical epidemiology and health sciences, two essential metrics—prevalence and incidence—are fundamental for understanding disease dynamics within a population. These measures enable public health officials, epidemiologists, and researchers to assess the burden of diseases, allocate resources effectively, and design impactful public health policies and interventions.
Prevalence indicates the proportion of individuals in a population who have a specific disease or health...

General Structure of a Vertebra

General Structure of a Vertebra

A typical vertebra, with the exception of the sacrum and coccyx, consists of a body, a vertebral arch, and seven different projections termed processes. The anterior portion of the vertebrae, the body, supports about half the body’s weight. The vertebral bodies progressively increase in size and thickness from the cervical region to the lumbar region of the vertebral column. The intervertebral discs present between the bodies of adjacent vertebrae firmly unites them, forming a continuous...

What is Variation?

What is Variation?

Apart from the measures of central tendency, distribution, outliers, and the changing characteristics of data with time, an important characteristic of any data set is its variation or spread. In some data sets, the data values are concentrated closely near the mean; in others, the data values are more widely spread out from the mean.
The range, standard deviation, standard error, and variance are the different measures of variation.
Range: The range is the difference between its maximum and...

Variation

Variation

An important characteristic of any set of data is the variation in the data. In some data sets, the data values are concentrated closely near the mean; in other data sets, the data values are more widely spread out from the mean. The most common measure of variation, or spread, is the standard deviation, which is the square root of variance.
When independent and dependent variables are plotted on a scatter plot, the slope of a line is a value that describes the rate of change between the two...

Conservative Site-specific Recombination and Phase Variation

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...

Anatomical Positions

Anatomical Positions

In anatomy, several standard anatomical positions are used as references for describing the position and orientation of different body parts. These positions help provide a common frame of reference when discussing anatomical structures. The anatomical position is the standard reference point for describing the body's position and orientation. In this position:
The body is upright, facing forward, and standing erect.
The feet are parallel and flat on the floor.
The arms are hanging by the...

Articles linked to this work by shared authors, journal, and citation graph.

Generative Artificial Intelligence Performance on University-Level Human Anatomy Examinations: A Structured Narrative Review and Proposed MATRIX-Anatomy Framework.

Clinical anatomy (New York, N.Y.)·2026

The Norton Scale at Admission Improves APACHE II-Based Mortality Prediction in the Intensive Care Unit: A Retrospective Cohort Study of 5775 Patients.

Medicina (Kaunas, Lithuania)·2026

Beyond Universal Coverage: The Magnitude of the Oral Health Equity Gap Between Socially Excluded Children and a Reference Paediatric Population Within a Single Spanish Setting.

Children (Basel, Switzerland)·2026

Tobacco Use, Stigma, and Coping in Lung Cancer: A Systematic Review of Their Psychosocial Interactions and Clinical Implications.

Current oncology (Toronto, Ont.)·2026

Oral Health Status, Oral Hygiene, and Behavioural Factors Among Disadvantaged Children: A Cross-Sectional Comparison Between the Peruvian Amazon and Valencia, Spain.

Dentistry journal·2026

Double Burden of Malnutrition and the Relationship Between Reported Intestinal Parasitosis and Anemia in School-Aged Children from a Peri-Urban Community of Limpio (Paraguay): A Cross-Sectional Study.

Nutrients·2026

See all related articles