Cranial-atlantoaxial vertebrae-relationships: a morphometric study

Rana A. Aziz Altae¹, Tara Farooq Kareem², Sabeeh Sameer Ibrahim³, Shams Nameer Qasim Al-Qadhi³, Rafal Raed Kadhem Aljanabi³, Younis A. Rasheed⁴

 

1 – Department of Anatomy, Baghdad University, College of Medicine. Baghdad, Iraq.

2 – Department of Surgery, Baghdad University, College of Medicine. Baghdad, Iraq.

3 – Baghdad University, College of Medicine. Baghdad, Iraq.

4 – Department of Surgery/Orthopedic, Al-Iraqia University, College of Medicine. Baghdad, Iraq.

The skull or the neurocranium is the bondy part protecting the brain, while the atlanto-axial complex is the one responsible for prtecting the spinal cord during it’s jurney from the brain to the spinal canal. Understanding these relationships is essential for surgical planning, biomechanical analyses, and diagnosing abnormalities in the craniovertebral junction. The findings of this study contribute to a more comprehensive understanding of the anatomical variations and correlations within this complex region. This study investigated the morphometric relationship between the skull’s biparietal diameter and the atlanto-axial complex morphometry-a crucial region for head movement and spinal cord protection.

Materials and methods. Seventy-five patients who underwent brain CT scans were included. Various measurements were obtained, including the biparietal diameter (BPD), anterior-posterior (AP) diameter, and inner cross-sectional area (CSA) of the skull. Measurements of the atlas vertebra, specifically the atlas transverse diameter, atlas AP inner diameter (with and without dens), and atlas inner area space were also taken from the CT scans. CT scans were performed using a Siemens 64 slice multidetector scanner, and 3D multiplanar reconstruction was employed to facilitate accurate measurements.

Results. There was a strong positive correlation between the biparietal skull diameter (BPD)and the inner skull surface area in males, females, ages more than and less than 40, also there was strong positive correlation between the skull inner surface area and the atlas inner surface area, however there was only strong positive correlation between the skull BPD and the atlas inner traverse diameter in those older than 40 years. Otherwise there was weak correlation between the skull BPD and other atlanto-axial measurements.

Discussion. The atlas-axis complex is highly differentiated in mammals, reflecting adaptations for head movement and stability The atlas and axis vertebrae are unique among the cervical vertebrae, as they are highly specialized for head movement and stability. The atlas lacks a vertebral body and spinous process, while the axis has a prominent dens that articulates with the atlas. This unique morphology allows for a wide range of head movements, including flexion, extension, and rotation.[10]

Understanding the relationship between skull dimensions and atlas morphology may have significant implications for the diagnosis and management of conditions affecting the craniovertebral junction. [11] For instance, certain genetic syndromes or developmental disorders known to affect skull growth may also impact the development of the atlas, predisposing individuals to craniovertebral instability or neurological compression. By elucidating the correlations between BPD and atlas morphometry, clinicians may be better equipped to identify individuals at risk for these complications and implement preventive or therapeutic interventions. Additionally, a comprehensive understanding of these relationships can inform the design of more effective surgical strategies for managing craniovertebral junction abnormalities [6, 12].

Conclusion. There was a strong positive correlation between the biparietal skull diameter (BPD) and the inner skull surface area in males, females, ages more than and less than 40, also there was strong positive correlation between the skull inner surface area and the atlas inner surface area, however there was only strong positive correlation between the skull BPD and the atlas inner traverse diameter in those older than 40 years.

 

Keywords: biparietal diameter; atlanto-axial complex; morphometry; neurosurgical; CT scan.

 

Corresponding author: Rana A. Aziz Altae, e-mail: Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript

For citation: Rana A. Aziz Altae, Tara Farooq Kareem, Sabeeh Sameer Ibrahim, Shams Nameer Qasim Al-Qadhi, Rafal Raed Kadhem Aljanabi, Younis A. Cranial-atlantoaxial vertebrae-relationships: a morphometric study. REJR 2026; 16(1):6-19. DOI: 10.21569/2222-7415-2026-16-1-6-19.

Received: 11.03.26 Accepted:            14.04.26