A, Site of entry of branches of the internal carotid, anterior choroidal, and anterior and middle cerebral arteries into the anterior perforated substance. The anterior perforated substance is located between the frontal and temporal lobes and is bordered anteriorly by the medial and lateral olfactory striae, laterally by the limen insulae, posteriorly by the optic tract and temporal lobe, and medially extends above the optic nerve and chiasm to the interhemispheric fissure. The A1 segment of the anterior cerebral artery gives rise to branches (blue) that enter the medial half of the anterior perforated substance above the optic nerve and chiasm. The internal carotid (purple) and anterior choroidal arteries (red) give rise to branches that enter the posterior part of the central portion of the anterior perforated substance. The middle cerebral artery gives rise to the medial (brown), intermediate (orange), and lateral lenticulostriate arteries (green) that enter the middle and posterior portions of the lateral half of the anterior perforated substance. The re-current artery (yellow) sends branches into the anterior half of the full mediolateral extent of the anterior perforated substance. The olfactory tract divides the frontal lobe between the gyrus rectus and the orbital gyri. B, Relationship of anterior perforating arteries to the deep cerebral structures. Superior view with all of the right cerebral hemisphere and the superior part of the left cerebral hemisphere removed. The site of the anterior perforated substance is shown on both sides by dotted lines. The deep neural structures above the anterior perforated substance are shown on the left side. The transverse section of the left cerebrum extends through the caudate nucleus, thalamus, globus pallidus, putamen, the anterior limb, genu, and posterior limb of the internal capsule, and the frontal horn and atrium of the lateral ventricle. The right side shows the site of origin of the perforating branches to the anterior perforated substance. The branches to the anterior perforated substance pass through the deep structures directly above the anterior perforated sub-stance and spread posteriorly to supply larger parts of the caudate nucleus, putamen, internal capsule, and the adjacent parts of the globus pallidus and thalamus. The C4 branches (purple) fuse the genu of the internal capsule, and the adjacent part of the globus pallidus, posterior limb of the internal capsule, and thalamus. The anterior choroidal branches (red) supply the medial two segments of the globus pallidus, the inferior part of the posterior limb of the internal capsule, and the anterior and ventrolateral nuclei of the thalamus. The lateral (green) and intermediate groups (orange) of lenticulostriate arteries pass through the putamen and the adjacent part of the globus pallidus and arch medially and posteriorly (arrows) to supply almost the entire anterior-to-posterior length of the upper part of the internal capsule and the body and head of the caudate nucleus. The medial lenticulostriate arteries (brown) irrigate the lateral part of the globus pallidus, the superior part of the anterior limb of the internal capsule, and the anterosuperior part of the head of the caudate nucleus. The A1 branches (blue) supply the genu of the internal capsule and the anterior part of the globus pallidus, and may extend to the adjacent part of the posterior limb of the internal capsule and, less commonly, to the thalamus. The recurrent artery (yellow) supplies the most anterior and inferior part of the head of the caudate nucleus and putamen, and the adjacent part of the anterior limb of the internal capsule. (Images courtesy of AL Rhoton, Jr.)