Structural Anatomy
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/21669
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Browsing Structural Anatomy by Author "Maddux, Scott D."
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Item Sexual Dimorphism in the Trochlear Angle of the Humerus: A preliminary investigation in Hunter-Gatherers and Agriculturalists(2018-03-14) Maddux, Scott D.; Pennavaria, AlexaPurpose: Previous research has argued the elbow “carrying angle” to be sexually dimorphic in humans, with females exhibiting greater abduction of the supinated forearm at full extension. Moreover, it is generally assumed that the trochlear angle of the humerus is the primary skeletal basis of the carrying angle, and thus, may independently provide a reliable osteological indicator of sex in forensic, bioarchaeological, and paleoanthropological contexts. Methods: Here, we employed the software TPSDig2 to derive trochlear angles from photographs of humeri collected on 40 (17 female/23 male) adult Archaic-period Amerindian hunter-gatherers and 54 (24 female/30 male) adult Medieval European agriculturalists. Due to handedness, angles from left and right humeri were averaged for each individual, with asymmetry assessed by subtracting the more acute angle from the more obtuse angle irrespective of actual left/right siding. Results: Although based on small sample sizes, males and females were not found to be significantly different from each other in either the Amerindian (t=1.5, p=0.13) or European (t=-1.3, p=0.26) samples. With both sexes pooled, the Amerindian sample exhibited more acute trochlear angles (t=4.64, p Conclusions: While failing to support the trochlear angle as a diagnostic sex indicator, our results are consistent with previous research generally demonstrating elevated levels of upper limb asymmetry in hunter-gatherer populations — asymmetries typically attributed to reliance on activities requiring greater unilateral loading of the dominant limb. Accordingly, the results of this study may indicate that more acute trochlear angles (less forearm abduction) reflect higher levels of biomechanical loading. Thus, sexual dimorphism in the carrying angle, if/when present, may be dependent on sex-specific activity patterns.Item Thermoregulation and the Human Nose: Balancing Climatic and Energetic Factors(2018-03-14) Maddux, Scott D.; Kim, SuhhyunPurpose: Studies have shown that indigenous individuals from cold-dry climates exhibit longer, taller, and especially narrower nasal passages compared to equatorial counterparts, enhancing inspiratory air-conditioning (heating and moisturizing) capacity and reducing susceptibility to respiratory tract infections. Concurrently, due to increased demand for thermogenesis, cold-dry climates are also metabolically more expensive than tropical environments, necessitating greater volumetric intake of oxygen. Accordingly, recent research has suggested that while a narrower nose enhances inspiratory air-conditioning, the accompanying restriction on volumetric intake may necessitate increased nasal height to maintain sufficient intake of oxygen. The purpose of this study was to examine the relationship between nasal dimensions, climate, and the metabolic demands. Methods: We employed 12 linear measurements collected from the nasal skeleton of 837 modern human crania from major geographic (Arctic Circle, Asia, Australia, Europe, Africa) and climatic (polar, temperate, hot-arid, tropical) zones. Anterior-posterior femoral head diameter (FHD) was further employed as a proxy for overall body size and metabolic requirements. Morphological, climatic, and geographic data were then employed in multivariate analyses. Results: Our results indicate that most breadth measurements of the nasal aperture and internal cavity are significantly correlated with climate (all significant R2 values between 0.29–0.51 with p-values 2 values between 0.67–0.78 with p-values 2 values between 0.36–0.56 with p-values 2 = 0.67, p = 0.0003), while nasal passage shape retained a significant relationship with climate (R2 = 0.66, p = 0.0004) with relatively tall/narrow airways associated with colder-drier environments. Conclusion: Collectively, these results support the assertion that physiological demands for temperature and moisture exchange are predominantly mediated by nasal passage breadth, with airway height representing a compensatory mechanism for ensuring a metabolically sufficient oxygen intake. Additional studies employing more direct measures of metabolic demands are accordingly warranted.