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Ossification and midline shape changes of the human fetal cranial base
1Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, United Kingdom. njeffery@liverpool.ac.uk
American Journal of Physical Anthropology
|December 12, 2003
Summary
Human fetal cranial base development shows shape changes like retroflexion and facial projection. Ossification, particularly in the sphenoid, correlates with these growth variations, influencing skull evolution.
Area of Science:
- Developmental biology
- Human anatomy
- Evolutionary biology
Background:
- Understanding ontogenetic changes in the cranial base is crucial for comprehending modern human skull evolution.
- Geometric morphometrics offers advanced methods for analyzing complex anatomical shape variations.
Purpose of the Study:
- To investigate midline shape variations of the human fetal basicranium and midface during prenatal development.
- To explore shape changes linked to endochondral ossification and reassess previous angular measurements.
- To analyze the role of ossification in modulating cranial base shape during human ontogeny.
Main Methods:
- Utilized geometric morphometric techniques on 54 formalin-preserved human fetuses.
- Acquired 10 midline cranial base and midface landmarks via high-resolution MRI.
- Quantified ossification areas in basioccipital, basisphenoid, and presphenoid cartilages as percentages of cranial base area.
Main Results:
- Observed shape variations consistent with cranial base retroflexion, anterior facial projection, and dorsal facial rotation with increasing fetal size.
- Identified growth variations centered on the midsphenoid area, with disproportionate changes in sphenoid height and length.
- Found small but significant correlations between presphenoid ossification and sphenoid shortening components of shape variation.
Conclusions:
- Prenatal human cranial base development exhibits significant shape variations, particularly around the midsphenoid.
- While direct causation is not established, bone formation (ossification) likely modulates cranial base shape development.
- These findings contribute to understanding the evolutionary trajectory of the modern human skull form.
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