Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands

Gross Anatomy and Microanatomy

Gary M. Heathcote, Timothy Bromage, Vincent J. Sava, Douglas B. Hanson, Bruce E. Anderson

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)1009-1021
Number of pages13
JournalAnatomical Record
Volume297
Issue number6
DOIs
StatePublished - 2014

Fingerprint

Micronesia
Mariana Islands
ancestry
anatomy
Electron Scanning Microscopy
Anatomy
scanning electron microscopy
Oculomotor Muscles
Microfilming
muscle
Oceania
muscles
cranium
Superficial Back Muscles
Pacific Ocean Islands
activity pattern
Skull
image analysis
Muscles
history

Keywords

  • Chamorros
  • Entheses
  • Functional anatomy
  • Occipital torus tubercle
  • Posterior supramastoid tubercle
  • Retromastoid process
  • SEM survey

ASJC Scopus subject areas

  • Anatomy
  • Histology
  • Ecology, Evolution, Behavior and Systematics
  • Biotechnology
  • Medicine(all)

Cite this

Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands : Gross Anatomy and Microanatomy. / Heathcote, Gary M.; Bromage, Timothy; Sava, Vincent J.; Hanson, Douglas B.; Anderson, Bruce E.

In: Anatomical Record, Vol. 297, No. 6, 2014, p. 1009-1021.

Research output: Contribution to journalArticle

Heathcote, Gary M. ; Bromage, Timothy ; Sava, Vincent J. ; Hanson, Douglas B. ; Anderson, Bruce E. / Enigmatic Cranial Superstructures Among Chamorro Ancestors From The Mariana Islands : Gross Anatomy and Microanatomy. In: Anatomical Record. 2014 ; Vol. 297, No. 6. pp. 1009-1021.
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