The mastoid triangle (Ma-Ast-Po) as a sexually dimorphic feature - a systematic review of 1604 human skulls and
Maria Eduarda Ramos Stefanel1, Lígia Melissa de Souza1, Fernanda Thomaz de Aquino Macedo1
1Division of Forensic Dentistry, Faculdade São Leopoldo Mandic, Rua José Rocha Junqueira 13, Office 03, Block E, Swift, São Paulo, Campinas, 13.045-755, Brazil.
Abstract:
The mastoid triangle is the area between the craniometric landmarks Mastoidale (Ma), Asterion (Ast) and Porion (Po), which has been studied in the field of physical anthropology as an alleged tool for sexual dimorphism. The evidence in the current scientific literature, however, is disputable. This systematic review aimed to find out how safe is the mastoid triangle for sexual dimorphism. A research protocol submitted to PROSPERO (CRD42023488216) was designed based on PRISMA-P. Pubmed, SciELO, LiLACS, LIVIVO, Open Gray and Open Access Theses and Dissertations were searched with structured strategies. The Joanna Briggs Institute manual was followed and the critical appraisal checklist for cross-sectional studies was used. The search found 14 eligible studies out of 2148 initially screened. The combined sample consisted of 1604 human skulls. Eight studies (57,14%) clearly encouraged the use of the mastoid triangle for sexual dimorphism, while three (21,42%) advised against it. All the studies had a low risk of bias (75-100%). The standardized mean difference between male and females was between 1.00 and 1.42 without statistically significant differences between geographic regions (p > 0.05). Expressive heterogeneity and large confidence intervals were detected, showing great variability across studies. A country-specific subgroup meta-analysis revealed lack of statistically significant differences based on geographic regions. This systematic review showed low level of evidence to support the use of the mastoid triangle as a tool for sexual dimorphism.
Related Concept Videos
01:08Overview of the Skull
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...
01:14Cranial Bones: Superior and Posterior View
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
01:27Cranial Bones: Lateral View
The temporal bone forms the lower lateral side of the skull. The temporal bone is subdivided into several regions. The flattened upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting...
01:22Sutures of the Skull
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...