The bilateral Inferior Frontal Gyrus, pars triangularis is a cortical subdivision of the inferior frontal gyrus located in the frontal lobe, forming part of the ventrolateral prefrontal cortex. In the HarvardOxford cort maxprob thr25 1mm Atlas, it is defined probabilistically and encompasses the triangular portion of the inferior frontal gyrus anterior to the pars opercularis and posterior to the pars orbitalis. This region is implicated in higher-order language and cognitive functions, including syntactic processing, semantic retrieval, and aspects of speech production, and it contributes to executive control and working memory processes. Functionally, it is closely associated with the left-hemisphere language network and is often considered a component of Broca’s region along with adjacent frontal areas. There is no dedicated Wikipedia page for this subdivision; a closely related structure is the Inferior frontal gyrus.
The bilateral Inferior Frontal Gyrus, pars triangularis (roughly corresponding to Brodmann area 45 within the Harvard-Oxford atlas) has been implicated in multiple imaging-genetics and GWAS studies linking cortical structure and function to specific genetic variants and neuropsychiatric traits. Large-scale neuroimaging GWAS (e.g., ENIGMA, UK Biobank) have associated variation in cortical thickness and surface area of this region with common variants in genes involved in neuronal development and synaptic signaling, including loci near HMGA2, KIAA0586, and various chromatin-modifying and axon guidance genes, though findings are generally polygenic and distributed rather than region-specific. Functionally, the pars triangularis, central to language, semantic processing, and cognitive control, has been highlighted in imaging-genetic studies of FOXP2 and CNTNAP2, where allelic variation influences activation and connectivity patterns in inferior frontal regions during language tasks. This region also shows structural and functional associations with genetic risk for psychiatric and neurodevelopmental conditions, including schizophrenia, autism spectrum disorder, and ADHD, in polygenic risk score analyses that relate higher genetic liability to altered inferior frontal morphology or activation. Additionally, GWAS of traits such as educational attainment, general cognitive ability, and reading/language skills have been linked to differences in inferior frontal cortical measures, though these reflect highly pleiotropic, small-effect variants spread across the genome rather than single, specific “IFG genes.” Overall, genetic influences on the pars triangularis appear strongly polygenic, overlapping with pathways for cortical development, synaptic plasticity, and language/cognitive control, and are typically detected through large-scale imaging-genetics consortia rather than targeted, region-exclusive associations.
Overview generated by GPT-4o (2026).
Region ID: 5
Hemisphere: bilateral
Atlas: HarvardOxford cort maxprob thr25 1mm
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Full Quality Version: Download MP4
Wali Sidiqyar*, Gaurav Rudravaram*, Elyssa M. McMaster, Trent M. Schwartz, Adam M. Saunders, Kurt G. Schilling, Bennett A. Landman "Introducing SPINS: A Shared Public Visualization Library of Neuroanatomical Structures." Medical Imaging with Deep Learning- short paper
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