The blood supply of the trigeminal nerve root, with special reference to the trigeminocerebellar artery.

The vasculature of the 29 roots of the trigeminal nerve was examined after india ink and gelatin had been injected into the vertebrobasilar arterial system. The trigeminal arteries were most often noted to arise from the superolateral pontine branch of the basilar artery (89.66%), and from the peduncular cerebellar branch of the anterior inferior cerebellar artery (75.86%). The trigeminocerebellar artery supplied two roots (6.89%) of the trigeminal nerves. The number of trigeminal arteries ranged from two to six, and their diameters ranged from 100 to 510 microns. Anastomoses among them were seen in 37.93% of the cases. The arteries formed the vascular rings around 58.61% of the roots. The motor portion of the trigeminal nerve most often received blood from the superolateral pontine artery (79.31%). The same artery most commonly supplied the rostral part of the sensory portion, which corresponded to the ophthalmic division of the trigeminal nerve. The superolateral artery, together with the inferolateral pontine artery and the peduncular cerebellar branch of the anterior inferior cerebellar artery, irrigated the middle part of the sensory portion, which corresponded to the maxillary division. The caudal part of that portion, which corresponded to the mandibular division, was commonly perfused by the peduncular cerebellar branch of the anterior inferior cerebellar artery. In this article, we discuss the possible clinical significance of the anatomic data observed.

The neurovascular relationships and the blood supply of the abducent nerve: surgical anatomy of its cisternal segment.

Twenty-eight abducent nerves were examined after injecting india ink and gelatin into the vertebrobasilar arterial system. All the abducent nerves were found to be crossed and/or penetrated by the surrounding vessels. The ventral surface of the nerves was crossed by the anterior inferior cerebellar artery (AICA) (75.0%), the posterior inferior cerebellar artery (17.85%), the common trunk of the AICA and posterior inferior cerebellar artery (7.14%), the internal auditory artery (14.28%), the anterolateral artery (46.43%), the pontomedullary artery (92.86%), and the corresponding veins (46.43%). The dorsal surface of the cisternal segment was crossed by the AICA (35.71%), the inferolateral pontine artery (10.71%), the anterolateral artery (82.14%), and the certain veins (46.43%). Sixty-four percent of the cisternal segments were penetrated by one or more of the following vessels: the AICA (25.0%), the anterolateral artery (17.86%), the pontomedullary artery (3.57%), and/or by the corresponding veins (42.86%). The majority of the cisternal segments of the abducent nerves were supplied by the anterolateral arteries (85.71%), and only some of them by the AICA (14.29%) or the pontomedullary artery (7.14%). The authors discuss the possible clinical significance of the anatomical data.

The surgical anatomy of the perforating branches of the basilar artery.

The perforating branches of the basilar artery were examined in 14 brain stems injected with india ink or methylmethacrylate. Three groups of the perforators were distinguished: the caudal, the middle, and the rostral. The caudal perforators varied in number from two to five and in diameter from 80 to 600 microns. In addition to their terminal branches, which entered the foramen cecum, the perforators occasionally branched off the pontomedullary artery, the pyramidal vessels, and the hypoglossal branches. The middle perforators arose either separately from the basilar artery or along with the basilar artery collateral branches. They ranged in number from five to nine and in diameter from 210 to 940 microns. The perforators gave rise to the pontomedullary artery (8.3%), the long pontine arteries (25.0%), and the anterolateral vessels (100%). The rostral perforators originated from the terminal part of the basilar artery (91.6%), as well as from the superior cerebellar artery (91.6%) and the posterolateral artery (16.6%). They varied in number from one to five and in diameter from 190 to 800 microns. The anastomoses among various perforating vessels were noted in 41.6 to 66.6% of the cases. The authors discussed the possible clinical significance of the anatomical data observed in this study.

Microvascular anatomy of the uncus and the parahippocampal gyrus.

The microanatomical examination of the uncal and the parahippocampal arteries was performed in 17 brain hemispheres injected with India ink and gelatin. The mentioned arteries may originate from the anterior choroidal artery, the internal carotid artery, the middle cerebral artery, and the posterior cerebral artery. The uncal or the unco-parahippocampal branches of the anterior choroidal artery were divided into rostral and caudal; the former were present in 70.6%, and the latter were present in 94.1%. The uncal or the unco-parahippocampal branches of the internal carotid artery, which originated 1.4 to 4.2 mm from its bifurcation site, existed in 58.8%. The same branches of the middle cerebral artery, which most often arose from the temporopolar artery, were present in 64.7%. Finally, these branches of the posterior cerebral artery, which usually arose from the anterior hippocampal artery, were observed in 47.1%. Large parahippocampal branches of the anterior choroidal artery were noted in 52.9%. The internal carotid artery and middle cerebral artery gave rise to these branches in 23.5 and 64.7%, respectively. The posterior cerebral artery always gave off 2 to 10 parahippocampal vessels. The largest of them originated within the rostral hippocampo-parahippocampal arterial complex. The authors discuss the microanatomical characteristics and possible clinical significance of the uncal and the parahippocampal arteries.

The thalamogeniculate perforators of the posterior cerebral artery: the microsurgical anatomy.

The thalamogeniculate (TG) arteries of 30 forebrain hemispheres were examined. These vessels varied from 2 to 12 in number (mean, 5.7), and from 70 to 580 microns in caliber (mean, 345.8 microns). The average caliber of all the TG vessels per posterior cerebral artery ranged from 700 to 3400 microns (mean, 1972 microns). The TG arteries most often originated as individual vessels; however, in 26.67% of the hemispheres examined they shared a common site of origin, and 33.33% of the hemispheres they arose from common stems. The common stems ranged from 320 to 800 microns in diameter (mean, 583 microns). The TG branches arose from the crural or ambient (P2) segment of the posterior cerebral artery in 80% of the hemispheres, from the P2 and the quadrigeminal (P3) segment in 20%, from both the distal segment of the posterior cerebral artery and the common temporal artery (13.33%), or from the distal segment and either the calcarine (3.33%) or parieto-occipital artery (3.33%). The TG arteries usually penetrated the medial geniculate body (100%), pulvinar thalami (80%), brachium of the superior colliculus (53.33%), or lateral geniculate body (13.33%). The collateral branches of the TG arteries were noted to reach the medial geniculate body (76.67%), pulvinar (70%), brachium of the superior colliculus (40%), crus cerebri (40%), and lateral geniculate body (6.67%). The anastomoses were present in 66.67%, usually between the TG vessels and the medial posterior choroidal artery (33.33%), or the mesencephalothalamic artery (26.67%). They ranged in number from 1 to 3 (mean, 1.2), and in caliber from 90 to 400 microns (mean, 197 microns).(ABSTRACT TRUNCATED AT 250 WORDS)

The perforating branches of the internal carotid artery: the microsurgical anatomy of their extracerebral segments.

The perforating branches of the internal carotid artery (ICA) were examined in 30 forebrain hemispheres. These branches were present in all the cases studied, and varied from 1 to 6 in number (mean, 3.1). Their diameters ranged from 70 to 470 microns (mean, 243 microns). The perforating branches arose from the choroidal segment of the ICA, that is, from its caudal surface (52.3%), caudolateral surface (34.1%), or caudomedial surface (13.6%). They rarely originated from the bifurcation point of the ICA (10%). The distance of the remaining 90% of the perforators from the summit of the ICA measured between 0.6 and 4.6 mm. The perforating branches most often originated as individual vessels, and less frequently from a common stem with another vessel or by sharing the same origin site with another perforator or with the anterior choroidal artery. The bifurcation of the ICA, which is a frequent site for cerebral aneurysms, is surrounded by many perforating branches. Hence, great care must be taken to avoid damage to these important vessels during operations in that region.

Microanatomy and possible clinical significance of anastomoses among hypothalamic arteries.

We examined anastomoses among the hypothalamic arteries in 14 human brains using an injection technique, microdissection, and a stereoscopic microscope. Five to 22 anastomoses (mean 10.1) were found in all 14 brains on each side, varying from 20 to 280 (mean 71) microns in diameter and from 0.1 to 5.3 (mean 1.52) mm long. A single hypothalamic artery may be connected to other vessels by one to 10 anastomoses. The anastomoses were channel-like or plexiform; both types may be ipsilateral or right-left. They connected the hypothalamic arteries "end-to-end," "end-to-side," and "side-to-side." The interconnected arteries ranged from 30 to 1,900 (mean 148) microns in diameter. Anastomoses were most frequent among the commissural arteries and in the distribution of the superior hypophyseal arteries and the tuberoinfundibular branches of the posterior communicating artery. The largest anastomoses were found among the tuberoinfundibular branches of the posterior communicating and internal carotid arteries, as well as among the premamillary arteries and the mamillary branches. We discuss the neurologic, neuroendocrinologic, and neurosurgical significance of the described anastomoses.

Distribution of the occipital branches of the posterior cerebral artery. Correlation with occipital lobe infarcts.

The occipital branches of the posterior cerebral artery were examined in 31 human brains. The authors determined the origin, course, and region of supply of each occipital branch: the parieto-occipital, calcarine, posterior temporal, and common temporal arteries, as well as the lingual gyrus artery. These vessels were found in all the brains examined except the lingual gyrus artery, which was present in only 8.3%. The occipital branches were noted to supply variable cortical regions. In addition, they sometimes took part in irrigation of deep forebrain structures. It was concluded that occlusion of a certain occipital artery may cause varying clinical signs and symptoms in different patients. The neurologic deficits that may occur following the isolated occlusion of individual occipital branches of the posterior cerebral artery are discussed.

Anastomoses among the thalamoperforating branches of the posterior cerebral artery.

Thirty-three injected human brains were examined, and anastomotic vessels were found in 26 (79%) of them. Anastomoses varied in number from one to six. The mean diameter was 148 microns, and the mean length was 3.3 mm. Anastomoses were observed among the following: the branches of the single thalamoperforating vessel of the posterior cerebral artery (PCA), the individual thalamoperforating arteries of the same PCA, the thalamoperforating vessels and branches of the basilar and superior cerebellar arteries on the same side, the peduncular branches of the PCA and ipsilateral branches of the basilar and superior cerebellar arteries, and the thalamoperforating arteries on one side and various contralateral vessels. Anastomoses could be important components of collateral circulation in occlusive cerebrovascular diseases.

Perforating branches of the middle cerebral artery. Microanatomy and clinical significance of their intracerebral segments.

Perforating branches of the middle cerebral arteries (MCA) were examined on the forebrain hemispheres of fourteen human brains. It was noticed that their intracerebral segments arose from the MCA main trunk, and its terminal and collateral (cortical) branches. They terminated in certain parts of the basal ganglia and internal capsule. The course, direction, shape, diameters and branches of these segments were examined in detail. Classification of all the vessels was made according to caliber. It was concluded that the size of lacunar infarcts depends on the caliber and ramification zone extent of the occluded perforating vessels. Diameters of the intracerebral segments of vessels ranged from 80 to 840 microns, of their terminal branches from 80 to 780 microns, and of the collateral branches from 50 to 400 microns. The average size of the ramification zone was: 41.6 X 15.5 mm for the entire perforating artery; 37.9 X 15.5 mm for the intracerebral segment; 23 X 13 mm for the terminal branches; 8.9 X 5.5 mm for larger collateral branches; and 2.6 X 1.4 mm for the smallest branches.

Perforating branches of the middle cerebral artery. Microsurgical anatomy of their extracerebral segments.

Perforating branches of the middle cerebral artery (MCA) were examined under magnification in 50 formalin-fixed brain hemispheres. Perforating vessels varied in number from three to 18, with an average of nine. The greater the number of vessels, the smaller was their diameter. In this study, the perforating arteries were divided into medial, middle, and lateral groupings. Those in the medial group usually arose directly from the MCA main trunk close to the carotid bifurcation. There were usually three vessels in the middle group, which originated not only from the MCA trunk, but also from the MCA collateral (cortical) branches. Common stems, when present, gave rise to individual perforating vessels and occasionally to thin olfactory and insular rami. Perforating arteries in the lateral group varied from one to nine in number. In addition to an origin from the MCA trunk, they also arose from cortical branches supplying the frontal and temporal lobes. The fact that lateral perforating vessels often originated from division sites and from terminal branches of the MCA is of clinical significance, because aneurysms are more commonly located at the MCA bifurcation. Anastomoses were not found among the perforating arteries. In two specimens, a fusion between a perforating artery and the MCA trunk was noted. Since the perforating vessels are obviously end arteries, injury to them must be avoided during operations for MCA aneurysms.

The isolated occlusion of the angular gyri artery. A correlative neurological and anatomical study--case report.

We examined a patient who had signs of a cerebral hemisphere lesion: right hemiparesis, facial weakness, right hemianopsy, acustico-mnestic dysphasia, "empty speech," acalculia, visuo-spatial agnosia and constructional apraxia, but without changes in consciousness. Taking into account clinical signs, computed tomography and carotid angiography findings, we concluded that our patient had an infarction zone in the left temporo-parieto-occipital region, as a consequence of the isolated angular gyri artery (ANG) occlusion. Some clinical signs were a direct effect of the ANG's occlusion. Namely, this artery supplies the cortical regions of great functional significance: the planum polare and temporale, the transverse temporal gyri, the superior and middle temporal gyri, the angular and supramarginal gyri, as well as the superior, middle and inferior occipital gyri. But the other symptoms and signs could be explained by the pathophysiological effect of the cerebral edema on regions supplied by the non-occluded branches of the middle cerebral artery.