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Objective To investigate the microsurgical anatomy of white matter fiber tracts and the important structures of the temporal lobe,and analyze its functional and clinical implications.Methods Ten formalin (100 g/L)-fixed human brain hemispheres were dissected using the Klingler fiber dissection technique,with the aid of an operating microscope at 4-25 magnification; the microsurgical anatomy of white matter fiber tracts and the important structures of the temporal lobe was observed.Results In the temporal lobe,a large number of complex white matter fiber tracts were noted locating lateral to the lateral wall of the temporal horn of lateral ventricle and superior to the roof wall.The vertical segment of the superior longitudinal fasciculus,occipitotemporopontine tract,inferior occipitofrontal fascicle,anterior and middle tracts of the optic radiation were located from lateral to the lateral wall of the temporal hom in turn; claustro-opercular and zinsulo-opercular fibers of the external and extreme capsules,auditory radiations,uncinate fasciculus,part of occipitotemporopontine tract,part of inferior occipitofrontal fascicle,anterior commissure,anterior and middle tracts of the optic radiation(including Meyer's loop),the ansa peduncularis and the stria terminalis were located from superior to inferior to the lateral wall of the temporal horn in turn.The lateral wall of the temporal horn of the lateral ventricle was composed of corpus callosum radiation,whose roof wall composed of the tail of caudate nucleus.Furthermore,amygdala composed of the anterior,tip and medial wall of the temporal horn,and the hippocampus constituted the medial wall of the temporal horn.The cerebral foot loop was an important medial structure of the temporal horn.Conclusion It's important in the clinical diagnosis and treatment to improve the knowledge and understanding of white matter fiber tracts and important structures of the temporal lobe.
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OBJECTIVE: There has been inconsistency about definition of the temporal stem despite of several descriptions demonstrating its microanatomy using fiber dissection and/or diffusion tensor tractography. This study was designed to clarify three dimensional configurations of the temporal stem. METHODS: The fronto-temporal regions of several formalin-fixed human cerebral hemispheres were dissected under an operating microscope using the fiber dissection technique. The consecutive coronal cuts of the dissected specimens were made to define the relationships of white matter tracts comprising the temporal stem and the subcortical gray matters (thalamus, caudate nucleus, amygdala) with inferior limiting (circular) sulcus of insula. RESULTS: The inferior limiting sulcus of insula, limen insulae, medial sylvian groove, and caudate nucleus/amygdala were more appropriate anatomical structures than the roof/dorso-lateral wall of the temporal horn and lateral geniculate body which were used to describe previously for delineating the temporal stem. The particular space located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus could be documented. This space included the extreme capsule, uncinate fasciculus, inferior occipito-frontal fasciculus, anterior commissure, ansa peduncularis, and inferior thalamic peduncle including optic radiations, whereas the stria terminalis, cingulum, fimbria, and inferior longitudinal fiber of the temporal lobe were not passing through this space. Also, this continued posteriorly along the caudate nucleus and limiting sulcus of the insula. CONCLUSION: The temporal stem is white matter fibers passing through a particular space of the temporal lobe located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus. The three dimensional configurations of the temporal stem are expected to give the very useful anatomical and surgical insights in the temporal lobe.