Relationships of the Temporal Lobe and Horn, Cranial Sutures, and Cortical Surfaces
Relationships of the Temporal Lobe and Horn, Cranial Sutures, and Cortical Surfaces. A, The relationships of the temporal lobe and horn, cranial sutures, and cortical surfaces of the right side. The coronal, sagittal, squamosal, and lambdoid sutures and the superior temporal line have been preserved and the dura has been opened. The pterion is located at the lateral margin of the sphenoid ridge near the junction of the coronal, squamosal, and frontosphenoid sutures and the lateral end of the greater sphenoid wing and stem of the sylvian fissure. The squamosal suture follows the anterior part of the posterior limb of the sylvian fissure before turning downward, at the level of the postcentral and supramarginal gyri, to cross the junction of the middle and posterior third of the temporal lobe. The pole of the temporal pole fits into the cupped inner surface of the greater wing of the sphenoid bone. Most of the lateral surface of the temporal lobe is positioned deep to the squamous part of the temporal bone; however, the posterior part of the lateral surface extends beyond the posterior limit of the squamous suture, deep to the parietal bone. The basal surface of the temporal lobe sits on the floor of the middle fossa and is positioned at the level of the upper edge of the zygomatic arch. B, The anterior view of a coronal section, at the level of the sylvian fissure on the right side and the sphenoid ridge in the left side. The pole of the temporal lobe extends forward under the sphenoid ridge and below the sylvian fissure. The inferolateral edge of the temporal lobe is positioned at the lateral edge of the floor of the middle fossa at the level of the zygomatic arch. C, The lateral view of the right temporal lobe. The temporal convexity is composed of the superior, middle, and inferior temporal gyri, which are divided by the superior and inferior temporal gyri. The inferior temporal gyrus folds around the lower margin of the hemisphere onto the lateral part of the basal hemispheric surface. The supramarginal gyrus wraps around the upturned posterior end of the sylvian fissure. D, That the frontal and parietal lobes, above the level of the sylvian fissure, have been removed. The upper lip of the calcarine sulcus, formed by the cuneus, has been removed to expose the lingula that forms the lower bank of the calcarine sulcus. The temporal horn and hippocampus lie deep to the middle temporal gyrus, which has been removed. The atrium lies deep to the supramarginal gyrus. The central sulcus ascends between the precentral and postcentral gyri. There is commonly a gyral bridge (red arrow) connecting the precentral and postcentral gyri below the lower end of the central sulcus, in which case the central sulcus does not open directly into the sylvian fissure. The calcar avis is the prominence in the lower part of the medial atrial wall overlying the deep end of the calcarine sulcus. E, Another right cerebral hemisphere with the frontal, parietal, and lateral part of the temporal lobes removed to expose the temporal horn. The choroid plexus, which attaches along the choroidal fissure, has been preserved. The inferior choroidal point, the anterior end of the plexal attachment in the temporal horn, is positioned behind the hippocampal head. The collateral eminence, located on the lateral side of the hippocampus, overlies the deep end of the collateral sulcus. F, That the choroid plexus has been removed in another specimen to expose the choroidal fissure located between the thalamus and fornix. The amygdala forms the anterior wall of the frontal horn. The uncal recess extends medially between the hippocampal head and the amygdala. The uncal recess is positioned lateral to the apex of the uncus. The upper surface of the parahippocampal gyrus is exposed medial to the fimbria. G, The enlarged view of another specimen. The choroidal fissure extends from the foramen of Monro to the inferior choroidal point located behind the head of the hippocampus. The choroid plexus, which attaches along the choroidal fissure, has been removed. The lower edge of the choroidal fissure in the temporal horn is formed by the fimbria of the fornix and the upper edge is formed by the thalamus. Opening the fissure between the lower surface of the thalamus and the fimbria of the fornix exposes the ambient cistern. The lateral geniculate body is exposed at the lower margin of the thalamus in the upper wall of the ambient cistern. The anterior wall of the temporal horn is formed by the amygdala, which tilts backward above, but is separated from the hippocampal head by the temporal horn. The uncal recess extends medially between the head of the hippocampus and amygdala. H, The superior view of a transverse section through the right temporal horn. The hippocampus and collateral eminence form the floor of the temporal horn. The amygdala occupies the anterior segment and the head of the hippocampus occupies the posterior segment of the uncus. The apex of the uncus is directed medially at the level of the uncal recess. The fimbria arises on the surface of the hippocampus. The upper surface of the parahippocampal gyrus is exposed medial to the fimbria. The collateral eminence overlies the deep end of the collateral sulcus, which extends along the basal surface on the lateral side of the parahippocampal gyrus. The hippocampus meets the calcar avis at the junction of the atrium and temporal horn. (Images courtesy of AL Rhoton, Jr.)
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