Original article / research
Morphometry of the Foramen Magnum in Relation to Cranial Parameters: Evidence from South Indian Skulls
Correspondence Address :
Dr. JE Benilsha,
Postgraduate Student, Anatomy, Sree Balaji Medical College and Hospital, Chennai-600044, Tamil Nadu, India.
E-mail: benilsha1996@gmail.com
Introduction: The Foramen Magnum (FM) is a critical anatomical region at the craniovertebral junction that transmits vital neurovascular structures and serves as an important landmark in forensic identification and neurosurgical procedures. Variations in dimensions and morphology exhibit population-specific patterns, making regional morphometric data essential for clinical and medico-legal applications.
Aim: To analyse the morphometric characteristics of the FM and its relationship with cranial dimensions in dry adult skulls from South India.
Materials and Methods: A cross-sectional study was conducted on 50 well-preserved adult dry skulls from the Department of Anatomy, Sree Balaji Medical College and Hospital, Chennai, Tamil Nadu, India. In the FM, Anteroposterior (APD) and Transverse Diameters (TD) were measured. The Maximum Cranial Length (MCL) and Maximum Cranial Breadth (MCB) were also measured using standardised osteometric instruments. Standard formulas were used to compute the Foramen Magnum Index (FMI) and the Cephalic Index (CI). Direct visual assessment was used to determine the FM shape. Descriptive statistics, linear regression, and Pearson’s correlation were used to evaluate the data, with a significance level of p<0.05.
Results: The mean APD and TD of the FM were 33.7±2.02 mm and 27.66±2.42 mm, respectively. The average length and breadth of the skull were 180.37±1.75 mm and 130.65±1.11 mm, respectively. The CI showed that all skulls were dolichocephalic (72.44±0.73). The most prevalent FM morphology was oval (64%), followed by tetragonal (36%). The TD of the FM and cranial breadth were significantly positively correlated (p=0.005). Cranial length and APD showed a slight and non significant correlation (p=0.238).
Conclusion: The sample had an oval FM morphology and a primarily dolichocephalic cranial pat-tern. While cranial length had little effect on anteroposterior diameter of FM, a coordinated transverse growth pattern was observed between cranial breadth and the TD of the FM. These results offer population-specific information with implications for neurosurgery and forensic anthropology.
Anthropometry, Cephalic index, Craniovertebral junction, Forensic anthropology, Osteometry, Skull base
DOI: 10.7860/JCDR/2026/88928.23755
Date of Submission: Mar 11, 2026
Date of Peer Review: Apr 02, 2026
Date of Acceptance: Apr 27, 2026
Date of Publishing: Jul 01, 2026
AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? No
• Was informed consent obtained from the subjects involved in the study? NA
• For any images presented appropriate consent has been obtained from the subjects. NA
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ETYMOLOGY: Author Origin
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