The authors dedicate this paper to the family of their colleague, friend, exceptional scholar, and exceptionally good man, the late Douglas B. Hanson.
Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands: Gross Anatomy and Microanatomy
Article first published online: 18 APR 2014
Copyright © 2014 Wiley Periodicals, Inc.
The Anatomical Record
Volume 297, Issue 6, pages 1009–1021, June 2014
How to Cite
Heathcote, G. M., Bromage, T. G., Sava, V. J., Hanson, D. B. and Anderson, B. E. (2014), Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands: Gross Anatomy and Microanatomy. Anat Rec, 297: 1009–1021. doi: 10.1002/ar.22920
- Issue published online: 22 MAY 2014
- Article first published online: 18 APR 2014
- Manuscript Accepted: 19 FEB 2014
- Manuscript Revised: 4 FEB 2014
- NSF and Max Planck
- College of Liberal Arts and Social Sciences, University of Guam
- occipital torus tubercle;
- retromastoid process;
- posterior supramastoid tubercle;
- functional anatomy;
- SEM survey
This study focuses on the gross anatomy, anatomic relations, microanatomy, and the meaning of three enigmatic, geographically patterned, and quasi-continuous superstructures of the posterior cranium. Collectively known as occipital superstructures (OSSs), these traits are the occipital torus tubercle (TOT), retromastoid process (PR), and posterior supramastoid tubercle (TSP). When present, TOT, PR, and TSP develop at posterior cranial attachment sites of the upper trapezius, superior oblique, and sternocleidomastoid muscles, respectively. Marked expression and co-occurrence of these OSSs are virtually circumscribed within Oceania and reach highest recorded frequencies in protohistoric Chamorros (CHamoru) of the Mariana Islands. Prior to undertaking scanning electron microscopy (SEM) work, our working multifactorial model for OSS development was that early-onset, long-term, and chronic activity-related microtrauma at enthesis sites led to exuberant reactive or reparative responses in a substantial minority of genetically predisposed (and mostly male) individuals. SEM imaging, however, reveals topographic patterning that questions, but does not negate, activity induction of these superstructures. Although OSSs appear macroscopically as relatively large and discrete phenomena, SEM findings reveal a unique, widespread, and seemingly systemic distribution of structures over the occipital surface that have the appearance of OSS microforms. Nevertheless, apparent genetic underpinnings, anatomic relationships with muscle entheses, and positive correlation of OSS development with humeral robusticity continue to suggest that these superstructures have potential to at once bear witness to Chamorro population history and inform osteobiographical constructions of chronic activity patterns in individuals bearing them. Further work is outlined that would illuminate the proximate and ultimate meanings of OSS. Anat Rec, 297:1009–1021, 2014. © 2014 Wiley Periodicals, Inc.