The Arteries of the Brain in Hare (Lepus europaeus Pallas, 1778)

Research into course and variability of brain arteries in hare were performed on 38 adult hares of both sexes (males 23 and females 15). The arteries were filled with a synthetic latex at a constant pressure introduced with a medical syringe to the left ventricle. The source of blood supply to the brain was internal carotid arteries, whose branches formed an arterial circle of the brain, vertebral arteries, and basilar artery as the result of its anastomosis. Variability focused on a method of departure of middle cerebral arteries, which were multiple vessels in 39.5% of cases and rostral cerebellar arteries. Caudal communicating arteries in hare comprised bilateral anastomosis of internal carotid arteries and final branches of the basilar artery. It stabilized the steady flow of blood to all parts of the brain. Caudal cerebral arteries comprised final branches of the basilar artery. The largest capacity of all the arteries of the brain was observed in the main trunk of the basilar artery. The capacity of these vessels was 4.53 mm³ on average. The factor of capacity of cerebral arteries in relation to weight of the brain reaches a high value in hare. Anat Rec, 298:1774–1779, 2015. © 2015 Wiley Periodicals, Inc.     

The systemic arterial pattern of the guinea pig: The head,thorax, and thoracic limb

The systemic arterial pattern of the guinea pig was studied to determine the arrangement of the major arterial trunks and their branches. Fifty-nine specimens were examined by dissection, angiography, and corrosion casting. The arterial arrangement was found to resemble a typical mammalian pattern, although some exceptions were noted. For example, the internal carotid arteries were small and of questionable significance in the cerebral blood supply. Instead, a major portion of the blood supply to the brain appeared to be provided by the internal ophthalmic arteries. In the thoracic region, large dorsal scapular arteries originated and were distributed in part to the large fat pad in the dorsal cervical region. Also, each vertebral artery arose as two separate rami that anastomosed a few millimeters from their origin. The arterial pattern of the thoracic limb presented no unusual features.     

Internal Ophthalmic Arteries Within the Brain‐Base Arterial System in Guinea Pig

In situ vascular specimens of the arterial circle were collected from 15 adult guinea pigs, both male and female. After specimen preparation, the vessels were filled with synthetic latex and subjected to analysis. Similar as in the case of other rodents, vertebral arteries were merged into basilar artery, further dividing into two short terminal branches. Distally, the terminal branches extend into caudal cerebral arteries. Rostral part of the arterial circle of brain is supplied with blood from maxillary arteries via external and internal ophthalmic arteries connected by a short anastomosis. This type of vascularity may probably be considered a functional analogy to the internal carotid arteries observed in other species. Rostral and caudal parts of the arterial circle of brain are connected by exceptionally long caudal communicating arteries. In author's opinion, the disputable contribution of internal carotid artery and the exceptional contribution of internal ophthalmic arteries in the cerebral blood supply in guinea pigs as compared to other rodents, warrants further research on the subject. Anat Rec, 301:887–891, 2018. © 2017 Wiley Periodicals, Inc.     

The hemodynamic effect of bilateral carotid artery ligation and the morphometry of the main communicating circuit in normotensive and spontaneously hypertensive rats

After reducing the number of patent conduit arteries to the brain by bilateral ligation of the carotid artery, the percentage decrease in blood pressure from the aorta to the internal carotid artery distal to the ligation was larger in spontaneously hypertensive rats than in normotensive rats. The pressure drop corresponded to the degree of hypertension as well as to morphometrically determined structural arterial alteration in the main communicating circuit, i.e. larger media to internal radius ratio and smaller internal radius in the posterior communicating arteries, the proximal part of the posterior cerebral arteries, the basilar artery and the vertebral arteries. The discrepancy between the sum of the luminal cross sectional areas of the communicating circuit and the luminal areas of the ligated conduit arteries was larger in the hypertensive than in the normotensive rats. It is to be expected that occlusion of conduit arteries to the brain will have a larger impact on the cerebral arterial perfusion pressure head in the presence of such hypertensive structural alterations known to increase flow resistance.     

Morphometry and Variability of the Brain Arterial Circle in Chinchilla (Chinchilla laniger,Molina)

Arterial circles of brains from 70 adult chinchillas were filled with synthetic latex. The arterial circle of the brain is formed as the result of vertebral arteries being merged into the basilar artery. Caudally, both vertebral arteries gave rise to the ventral spinal artery. The ventral spinal artery splits into tiny cerebellar vessels, the pontine and cochlear branches. Distally, the basilar artery ramified into two terminal branches that formed the arterial circle of brain, rostrally open in most cases (75%). The observed variability of the arterial circle of brain of chinchillas pertained to all elements of that circle. The greatest variability within the vessels of the circle of Willis in chinchillas was observed in 22 cases (31.4%) of internal ophthalmic arteries. In chinchillas, a trend toward slight variability within the arteries comprising the arterial circle of the brain was observed in 44 animals. This accounted for 62.8% of all cases. Only in three cases was the arterial circle of brain clearly symmetrical. At the same time, 23 animals (32.8%) revealed features of significant vascular variability within the brain base region. These consisted of disturbed geometry of the entire arterial circle, different levels of ramifications into individual arteries, as well as the number and diameter of arteries. No internal carotid arteries were observed in chinchillas apart from one atypical case in which the carotid artery extended unilaterally into the basilar artery. These investigations indicate on the significant variability of arterial circle in rodents. Anat Rec, 300:1472–1480, 2017. © 2017 Wiley Periodicals, Inc.     

Anatomic variations of anterior cerebral artery cortical branches

The anterior cerebral artery (ACA) is a major vessel responsible for the blood supply to the interhemispheric region. The ACA segment after the anterior communicating artery (AComA) origin is called the distal ACA and has central and cortical branches. The cortical branches are distributed in the different regions of the orbital and medial part of the brain. The objects of this study are the anatomical variations found in the distal ACA. In 76 hemispheres the ACA distal branches were injected with latex and dissected under microscope magnification. Vessel diameters and distances between vessel origins and anterior communicating artery were recorded and analyzed. Microsurgical dissection was carried out to demonstrate anatomic variations of these vessels. Average diameter of ACA at origin was 2.61 +/- 0.34 mm and average diameter of cortical branches diameter ranged from 0.79 +/- 0.27 mm to 1.84 +/- 0.3 mm. Distances between vessel origin and AComA ranged from 7.68 +/- 3.91 mm (orbitofrontal) to 112.6 +/- 11.63 mm (inferior internal parietal). This study found anatomical variations: a single (azygos) ACA was present in one case and three in three cases. Crossing branches of the distal ACA to the contralateral hemisphere were present in 26% of the cases. In some cases a single ACA may supply the posterior hemispheric region through crossing branches. This calls attention to potential bilateral brain infarcts due to a single unilateral ACA occlusion.     

Anatomical studies on the arteries of the brain of buffalo (Bubalus bubalis). I. The rete mirabile cerebri.

The arterial circulation to the brain of buffalo is accomplished through the rete mirabile cerebri. It is an interwined arterial mass located in the cavernous sinus on either side of the sella turcica and extend from foramen orbitorotundum to the sphenococcipital junction. The major contribution of blood reaches through the arteriae anastomotica and ramus anastomoticus, the branches of the internal maxillary artery. The vertebral and condyloid arteries form a plexus on basioccipital bone (plexus basioccipitalis). An emergent artery from the latter plexus bifurcates and joins the rete along its caudomedial angle. The internal carotid artery plays hardly any role in the cerebral circulation of buffalo.     

Systematization,Description, and Territory of the Middle Cerebral,Rostral, and Cerebroethmoidal Arteries on the Surface of the Brain of the Ostrich (Struthio camelus)

Thirty ostrich specimens were injected with red-dyed latex via the internal carotid arteries (Aa.) The middle cerebral and cerebroethmoidal arteries and their branches were systematized. The middle cerebral artery (a.) was always a single large vessel. On the right side, it had two, three, or one developed medial hemispheric branches in 46.6%, 26.7%, and 26.7% of cases, respectively. On the left side, one (36.7%), two (33.3%), and three (30%) developed medial hemispheric branches were observed. The middle cerebral artery had eight (40%), nine (20%), seven (16.7%), eleven (6.7%) ten (6.7%), twelve (3.3%), six (3.3%), and five (3.3%) developed lateral hemispheric branches on the right side and seven (46.7%), nine (13.3%), eight (13.3%), six (10%), five (10%), and ten (6.7%) on the left. Two (33.3%), four (20%), three (20%), one (16.7%), and five (10%) direct perforating branches of the middle cerebral artery were present on the right, and three (33.3%), two (30%), one (13.4%), six (10%), four (10%), and five (3.3%) were present on the left. The cerebroethmoidal artery, always present as a natural continuation of the rostral terminal branch of the brain's carotid artery and originating from the middle cerebral artery, was a large vessel that projected rostromedially, giving off the rostral cerebral artery shortly after its formation and continuing as the ethmoidal artery. The rostral cerebral artery was a single (90%) and double (10%) vessel on the right and a single (96.7%) and double vessel (3.3%) on the left. The ethmoidal artery was always a medium to large single vessel and was the natural continuation of the cerebroethmoidal artery, immediately after giving off the rostral cerebral artery. Anat Rec, 302:1187–1194, 2019. © 2018 Wiley Periodicals, Inc.     

Microvascularization of thalamus and metathalamus in common tree shrew (Tupaia glis)

The microangioarchitecture of the thalamus and metathalamus in common tree shrew (Tupaia glis) was studied using vascular corrosion cast/stereomicroscope and SEM technique. The arterial supply of the thalamus and metathalamus was found to originate from perforating branches of the posterior communicating artery, the posterior cerebral artery, the middle cerebral artery, and the anterior choroidal artery. These perforating arteries gave rise to numerous bipinnate arterioles which in turn, with decreasing vessel diameters, branched into a non-fenestrated capillary bed. Venous blood from the superficial parts of the thalamus and metathalamus was collected into the thalamocollicular vein, whereas venous blood from internal aspects of the thalamus was conveyed to the internal cerebral vein. Some venous blood from the most rostral part of the thalamus flowed into tributaries of the middle cerebral vein before draining into the cavernous sinus. Further, the thalamic and metathalamic vascular arrangement was found to be of centripetal type. In addition, thalamic arterial anastomosis was rarely observed. Thus, obstruction of thalamic blood supply could easily lead to thalamic infraction.     

Anomalous artery directly connecting the external and internal carotid arteries

An anomalous artery directly connecting the external with the internal carotid artery was encountered on the right side of a 68-year-old Japanese female cadaver. This anomalous artery (5 mm in diameter, 12 mm in length) branched out from the posterior aspect of the external carotid at the level of the origin of the lingual artery, ran obliquely upward posteriorly along the course of the hypoglossal nerve, and was confluent with the anterior aspect of the internal carotid artery. No other variations were found in the morphological aspects of, or in the anatomical relationships between, the carotid arteries and their surrounding structures on either side. The carotid body-like structure was observed at the carotid bifurcation and was innervated by small branches of the glossopharyngeal, the vagus and the sympathetic trunk. Embryologically, it is conceivable that this anomalous artery may have derived from the right second branchial arch artery, although there is no abnormality in other derivative structures of the second pharyngeal arch. There may have been no effect from this anomaly on the functions of the arterial blood flow and blood supply under normal circumstances in the present case, but this report may be of embryological significance and contribute some insight into the mechanisms of the formation of the carotid circulation systems.     

人外侧膝状体的血液供应及其临床意义

目的：为外侧膝状体（LGB）缺血所致的视野缺损提供形态学依据。方法：手术显微镜下观察成人和胎儿脑的LGB动脉的来源和微血管构筑,部分脑标本用组织切片方法观察营养LGB动脉的粥样硬化病理改变。结果：LGB营养动脉第一级来自颈内动脉和大脑后动脉,二级为脉络丛前动脉、脉络丛后外动脉和丘脑膝状体动脉,三级构成LGB的小动脉。50岁以上的标本,LGB的一、二级动脉有硬化改变的占88％,二级小动脉被阻塞占10％。结论：二级动脉在LGB内有各自的供血区,脉络丛前动脉是供应LGB前部和外侧部的唯一动脉,大脑后动脉营养LGB的其余部分。不同动脉的阻塞可导致不同种类的视野改变,是视野缺损的原因之一。     

Prevalence of arterial branches arising from the extracranial internal carotid artery on CT angiography

Although it is well known that arterial branches may rarely arise from the cervical internal carotid artery (ICA), their incidence has not been adequately evaluated on computed tomography angiography (CTA). We investigate the prevalence of congenital and non-congenital anomalous branches arising from the cervical ICA by a 5 year retrospective review of neck CTAs performed on 2,602 patients. We found a higher frequency of arteries arising from the ICA than suggested by the existing literature, including a 0.49 % prevalence of the occipital artery origin and a 6.25 % prevalence of the superior pharyngeal branch of (the pharyngeal trunk of) the ascending pharyngeal artery. In addition, six cases of recanalized intersegmental arteries providing collateral flow to the cervical ICA from the cervical vertebral artery were identified. This is the first large, retrospective CTA study evaluating the incidence of these anomalous vessel origins.     

Microsurgical anatomy of the maxillary artery for extracranial‐intracranial bypass in the pterygopalatine segment of the maxillary artery

The extracranial‐intracranial (EC‐IC) bypass using the maxillary artery (MA) has been successfully completed using a radial artery (RA) graft but the complicated anatomy and narrow exposure make it difficult. The purpose of this article is to define the microsurgical exposure of the MA through the middle fossa and describe the branches, diameter, and length of the MA available for the EC‐IC bypass in the sphenopalatine fossa and anterior part of the infratemporal fossa. 5 cadaveric specimens were dissected bilaterally (10 MA dissections) to define the microsurgical anatomy of the MA through an intracranial approach. The exposable branches of the MA at the level of the infratemporal and sphenopalatine fossae were the anterior deep temporal, posterior superior alveolar, and infraorbital arteries. The origin of each branch could be exposed. The available section of the MA for use as a donor vessel is between the origin of the anterior deep temporal artery and the infraorbital artery. The mean exposable length of the MA was 19.4 mm. The mean outer diameter of the donor MA was 3.2 mm. Tension‐free EC‐IC bypass was possible using a RA graft between the MA and the middle cerebral artery, the MA and the supraclinoid internal carotid artery (ICA), or the MA and the petrous ICA. Exposure of the MA at the infratemporal and sphenopalatine fossae is complicated but provides length and diameter suitable as a donor artery for the EC‐IC bypass. Clin. Anat. 31:724–733, 2018. © 2017 Wiley Periodicals, Inc.     

Persistent carotid-vertebral anastomosis associated with contralateral accessory middle cerebral artery

An exceptional case is reported of a complex anomaly of the brain arteries including low left carotid bifurcation, persistent carotid-vertebral anastomosis on the left and accessory middle cerebral artery on the right; the whole posterior circulation was only filled through the anomalous anastomotic vessel which joined with the vertebral artery because of a contralateral hypoplasic vertebral artery and the absence of both posterior communicating arteries. This association has not been previously reported in the literature. The embryological processes leading to these arterial anomalies are discussed. Risks related to a severe carotid stenosis or occlusion and to surgical or endovascular procedures in patients harboring these arterial anomalies are emphasized.     

Quantitative comparison of cerebral artery development in human embryos with other eutherians

The embryonic and early fetal human brain is known to undergo extraordinary expansion of its cellular population during embryonic and early fetal life, and is critically dependant on a steady supply of nutrients and oxygen for proper brain development. Quantitative analysis of the internal radius of the aorta and cerebral arteries in a range of eutherian mammals has been used to compare arterial flow to the developing human brain with that to the brains of non‐human eutherians. Human embryos showed a much steeper rise of internal radius of the aorta with increasing body size than the embryos of non‐human eutherians, but the thickness of the aorta rose at the same pace relative to body size in both humans and non‐humans, suggesting that aortic pressure is similar in all eutherian embryos of a similar size. The sums of internal radii of both the internal carotids and vertebral arteries of human embryos raised to the fourth power were much lower at embryonic stages (less than 22 mm body length) than in non‐human eutherians, were similar between humans and non‐humans at 22–30 mm body length, and exceeded the non‐humans at body lengths of more than 30 mm. The relative size of the internal calibre of the cerebral feeder arteries (internal carotid and vertebral) to the aorta did not change between embryonic and fetal sizes in either humans or non‐humans. The findings suggest that the developing human brain may actually receive less blood flow at embryonic sizes (less than 22 mm body length) than do other mammalian embryos of a similar body size, but that internal carotid and vertebral flow is higher in human fetuses (body length greater than 30 mm) than in developing non‐humans of the same body size. Increased flow to the developing human brain relative to non‐humans is achieved by simultaneous increases in both aortic and cerebral feeder artery internal calibre.     

Origins and pathways of cerebrovascular nerves storing substance P and calcitonin gene-related peptide in rat

Origins and pathways of cerebrovascular substance P- and calcitonin gene-related peptide-positive nerves in rat were studied by immunohistochemistry combined with denervation experiments and retrograde axonal tracer technique. The two peptides have been found to coexist in one and the same neuron. After sectioning of the nasociliary nerve bilaterally the substance P/calcitonin gene-related peptide fibers in the rostral half of the circle of Willis and its branches were eliminated, whereas the number decreased in the caudal half of the circle of Willis and rostral two thirds of the basilar artery. Substance P/calcitonin gene-related peptide fibers in the internal carotid arteries, the caudal third of the basilar artery and the vertebral arteries were not affected by the nerve section. After application of the retrograde axonal tracer True Blue onto the proximal segment of the middle cerebral artery the dye accumulated in several Substance P/calcitonin gene-related peptide-containing cells in the ophthalmic division of the ipsilateral trigeminal ganglion and in a few cells in the maxillary trigeminal division and in the internal carotid miniganglion. No other cranial ganglia accumulating the dye contained any substance P/calcitonin gene-related peptide-positive cells. It is concluded that the rostral portion and part of the caudal portion of the cerebral vessels are innervated by substance P/calcitonin gene-related peptide-containing fibers from the trigeminal ganglion and the internal carotid miniganglion. The great majority of trigeminal fibers reach the vessels via the nasociliary nerve of the ophthalmic division, which enters the cranial cavity through the ethmoidal foramen, whereas fibers from the miniganglion project directly to the bypassing internal carotid artery. A probable pathway for the fibers from the maxillary division is suggested. The caudal portion receives, in addition, a supply from other sensory ganglia (lower cranial and/or upper cervical dorsal root ganglia).     

Development of AChE-positive, NA-containing and VIP- and NPY-immunoreactive nerves in the major cerebral arteries of the rat

Summary The development of cerebrovascular nerves containing noradrenalin (NA), acetylcholinesterase (AChE), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) was studied in rats from before birth to adulthood. All these nerves entered the cranial cavity along the cerebral carotid, internal ethmoidal, and vertebral arteries during the early stages of development, but the subsequent growth and distribution of NA-containing and NPY-immunoreactive (IR) nerves differed greatly from that of AChE-positive and VIP-IR nerves. NA-containing and NPY-IR nerves extended rapidly from the cerebral carotid artery and spread over all the major arteries of the internal carotid system by postnatal day 3, as well as descending the posterior ramus of the cerebral carotid to mingle with nerves from the vertebral artery around the mid-basilar artery by day 5. AChE-positive and VIP-IR nerves from the internal ethomoidal artery covered the whole internal carotid system during the first postnatal week, and projected to the upper basilar artery after the second week, while those from the cerebral carotid artery remained limited to the middle cerebral artery throughout development. By day 21, all major arteries of the internal carotid system had dense plexuses of the four nerve types that were similar to those observed in adult rats. The vertebrobasilar system also had a well-organized network of NA-containing and NPY-IR nerves, but only a poor supply of AChE-positive and VIP-IR nerves. Even on day 30, the latter two nerve types were sometimes absent from the middle to caudal basilar artery, owing to a lack of interdigitation by nerves from the internal ethomoidal and vertebral arteries.     

Quantitative comparison of cerebral artery development in metatherians and monotremes with non‐human eutherians

A quantitative comparison of the internal diameters of cerebral feeder arteries (internal carotid and vertebral) and the aorta in developing non‐human eutherians, metatherians and monotremes has been made, with the aim of determining if there are differences in cerebral arterial flow between the three infraclasses of mammals such as might reflect differences in metabolism of the developing brain. There were no significant differences between eutherians and metatherians in the internal radius of the aorta or the thickness of the aortic wall, but aortic internal radius was significantly smaller in developing monotremes than therians at the < 10 mm body length range. Aortic thickness in the developing monotremes also rose at a slower rate relative to body length than in metatherians or eutherians. The sums of the internal calibres of the internal carotid and vertebral arteries were significantly lower in metatherians as a group and monotremes compared with non‐human eutherians at body lengths up to 20 mm and in metatherians at > 20 mm body length. The internal calibre of the internal carotids relative to the sum of all cerebral feeder arteries was also significantly lower in monotremes at < 10 mm body length compared with eutherians. It was noted that dasyurids differed from other metatherians in several measures of cerebral arterial calibre and aortic internal calibre. The findings suggest that: (i) both aortic outflow and cerebral arterial inflow may be lower in developing monotremes than in therians, particularly at small body size (< 20 mm); (ii) cerebral inflow may be lower in some developing metatherians than non‐human eutherians; and (iii) dasyurids have unusual features of cerebral arteries possibly related to the extreme immaturity and small size at which they are born. The findings have implications for nutritional sourcing of the developing brain in the three infraclasses of mammals.