No attempt is made to provide references for the original descriptions of gross anatomical structures, but synonyms are mentioned to accommodate the differences in terminology used by anatomists, pathologists, and radiologists in textbooks and other literature.īulges on the lateral sides of the forebrain in insectivores (considered ancestral to primates) are anatomically related to the temporal bone and contain cortical areas and other structures such as the hippocampus and amygdala that are medially located in the temporal lobes of the human brain. A few historical references are included to remind readers that many of the “discoveries” made with modern imaging techniques simply confirm what has been known about the temporal lobe for many years. References are provided for further reading, especially in areas where there is clinical interest or controversy or where anatomical details are not easily found in ordinary textbooks of neuroanatomy. Some physiological and pathological correlates are mentioned, but this is primarily an anatomical account. In this paper, I attempt to explain the positions of the parts of the normal human temporal lobe in relation to one another and to nearby structures. This article also reviews arterial supply, venous drainage, and anatomical relations of the temporal lobe to adjacent intracranial and tympanic structures. The temporal lobe contains much subcortical white matter, with such named bundles as the anterior commissure, arcuate fasciculus, inferior longitudinal fasciculus and uncinate fasciculus, and Meyer’s loop of the geniculocalcarine tract. Its major projections are to the septal area and prefrontal cortex, mediating emotional responses to sensory stimuli. The amygdala receives input from the olfactory bulb and from association cortex for other modalities of sensation. The amygdala comprises several nuclei on the medial aspect of the temporal lobe, mostly anterior the hippocampus and indenting the tip of the temporal horn. The choroid fissure, alongside the fimbria, separates the temporal lobe from the optic tract, hypothalamus and midbrain. The largest efferent projection of the subiculum and hippocampus is through the fornix to the hypothalamus. Association fibres connect all parts of the cerebral cortex with the parahippocampal gyrus and subiculum, which in turn project to the dentate gyrus. The hippocampus is an inrolled gyrus that bulges into the temporal horn of the lateral ventricle. The hippocampal formation, on the medial side of the lobe, includes the parahippocampal gyrus, subiculum, hippocampus, dentate gyrus, and associated white matter, notably the fimbria, whose fibres continue into the fornix. Only primates have temporal lobes, which are largest in man, accommodating 17% of the cerebral cortex and including areas with auditory, olfactory, vestibular, visual and linguistic functions.
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