This chapter, the last of three showing sections of entire human brains, illustrates para sagittal planes. Forebrain structures continue to be emphasized, but parts of the brainstem and cerebellum are indicated as well. The organization of various functional systems in the forebrain (e.g., thalamus, hippocampus) is presented in
Chapter 8 .
Colored diagrams showing typical areas of arterial supply in each section are provided in this and the preceding two chapters. We simplified these in two major ways. First, arterial territories are shown as sharply demarcated from each other when in reality there is significant interdigitation and overlap. Second, perforating arteries arise from all the vessels of the circle of Willis, but we lumped together those from the posterior communicating and posterior cerebral arteries and those from the anterior communicating and anterior cerebral arteries.
The axial sections from
Figs. 6.3G and 6.3N
, used in much of this chapter to indicate planes of section.
The planes of section shown in this chapter, indicated on three-dimensional reconstructions.
(Courtesy Dr. John W. Sundsten, Department of Biological Structure, University of Washington School of Medicine.)
(A–P) Sixteen para sagittal sections of the right half of a brain. The sections are arranged in a lateral-to-medial sequence extending from the insula to the midline. Anterior is toward the left, so the view is as though you were backing through the brain, always looking from inside the brain out toward the lateral sulcus. (A) The first section passes tangentially through the insula (5) and shows nicely how the lateral sulcus (6) leads to it and the circular sulcus (4) outlines it. The precentral (1) and postcentral (3) gyri can also be seen, separated from each other by the central sulcus (2) , which, cut obliquely, seems deeper than it really is.
(B) The circular sulcus (1) is still present, partially surrounding the insula (2) , but now the plane of section begins to reveal structures just deep to insular cortex—in this case the claustrum (3, 6) . The most lateral part of the lateral ventricle, the inferior horn (5) , also appears, with the tail of the caudate nucleus (4) cut tangentially in its wall.
Now the putamen
appears and the claustrum
, a sheet of gray matter that covers the curved lateral aspect of the putamen, appears to partially surround it in this two-dimensional view. The tail of the caudate nucleus
is cut tangentially in the wall of the inferior horn of the lateral ventricle
. Across the ventricle, the hippocampus
makes its appearance. Shown enlarged in
continues to increase in size, still partially surrounded by the claustrum
. The tail of the caudate nucleus
is now cut in two places as it curves into the temporal lobe with the inferior horn of the lateral ventricle
. The posterior horn of the lateral ventricle
extends back toward the occipital lobe. The hippocampus
increases in size, and the amygdala
appears at its anterior end. A downward extension
of the putamen merges with the amygdala, much as the tail of the caudate nucleus merges with both in a nearby plane (see
). Fibers that have collected from the temporal lobe and will cross in the anterior commissure
mass underneath the putamen.
The globus pallidus (
, part of its external segment) appears adjacent to the putamen
, with fibers of the anterior commissure
traveling beneath them. The caudate nucleus is again cut twice, once
as it curves around from the body to the inferior horn of the lateral ventricle and a second time
as it merges with the amygdala
. Fibers of the fimbria
are cut tangentially as they emerge from the hippocampus
. An enlarged mass of choroid plexus (
, the glomus) protrudes into the atrium of the lateral ventricle
, and the posterior horn of the ventricle
extends back into the occipital lobe. Shown enlarged in
Now both the internal
segments of the globus pallidus can be seen adjacent to the putamen
. The plane of section has reached the thalamus; the pulvinar
appears, as well as the lateral geniculate nucleus
with the optic tract
ending in it. The fimbria, cut tangentially in
, is now cut in two places
. The posterior horn of the lateral ventricle
appears in this plane to be a detached cavity in the occipital lobe but is in fact continuous with the atrium
The head of the caudate nucleus
appears, with fibers of the anterior limb of the internal capsule
emerging from the cleft between it and the putamen
. Strands of gray matter
extend between the caudate nucleus and putamen, emphasizing the common embryological origin and similar pattern of connections of these two parts of the striatum. The most lateral of the deep cerebellar nuclei, the dentate nucleus
, can be seen, and the parietooccipital sulcus
is now distinct. Shown enlarged in
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