scholarly journals Incomplete circle of Willis due to the bilateral abnormal origin of posterior cerebral arteries and bilateral absence of posterior communicating arteries

2014 ◽  
Vol 3 (1) ◽  
pp. 40
Author(s):  
MohandasK. G. Rao ◽  
M Sapna ◽  
Nagabhooshana Somayaji ◽  
LS Ashwini
Keyword(s):  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Bilateral Absence

Exposure of the anterior part of the circle of Willis in the dog

1974 ◽  
Vol 41 (1) ◽  
pp. 107-112
Author(s):  
Shigeaki Hori ◽  
Williamina A. Himwich
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Content Type ◽  
Anatomical Characteristics ◽  
Fine Print

✓ A technique for exposing the vessels in the anterior part of the circle of Willis in the dog is described. Some of the physiological and anatomical characteristics of the anterior communicating and the anterior cerebral arteries are discussed.

scholarly journals Study of variations of the anterior cerebral artery in human brain

2013 ◽  
Vol 02 (03) ◽  
pp. 122-127
Author(s):  
Bishwajeet Saikia ◽  
Kunjalal Talukdar ◽  
Joydev Sarma ◽  
Amitav Sarma ◽  
Sandeep Madaan
Keyword(s):  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Cerebral Arteries ◽  
Initial Step ◽  
Circle Of Willis ◽  
Anatomical Distribution ◽  
Surgical Interventions ◽  
Medical College ◽  
The Individual ◽  
Considerable Individual Variation

Abstract Background and aims: Stroke, the most frequent expression of cerebrovascular disease is one of the leading causes of death and disability throughout the world. The manifestations are largely accounted by the anatomical distribution of the stems and branches of the circle of Willis supplying the brain. Considerable individual variation exists in the pattern and caliber of the individual vessels forming the circle of Willis, which may possibly impair the collateral blood flow. The knowledge of these variations thus, becomes essential for medical as well as surgical interventions. There may possibly be some regional variations in the cerebral arteries not mentioned in standard available texts. Thus, the regional based study of variations present becomes essential. The present study aims to focus on the variation of one of such branches, the anterior cerebral artery (ACA) in the population of Assam, India. Material and Methods: The ACAs of 70 human cadaveric brains were examined by gross dissection in the department of Anatomy and Forensic medicine in Gauhati Medical College. Results: Hypoplastic A-1 segment were found in 7% cases, Hypoplastic A-2 segment in 2.85% cases, Buttonhole formation in 8.57% cases and aneurysmal dilatation in 1.42% cases. The results were compared with that of other authors and variations noted. Conclusion: The present study of ACA using gross dissection is an initial step in providing a reference to the healthcare professionals in the region of Assam. Based on this further studies using newer imaging methods should be carried out to correlate the manifestations clinically.

scholarly journals Average dimensions of the vessels at the base of the brain and the embryological basis of its variations

2013 ◽  
Vol 02 (04) ◽  
pp. 180-189
Author(s):  
Iqbal S.
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Cerebral Dominance ◽  
Circle Of Willis ◽  
Detailed Knowledge ◽  
Differential Growth ◽  
Ischemic Attack ◽  
The Individual ◽  
The Right ◽  
The Brain

Abstract Background and aims: The cerebral circulation is constantly maintained by the anastomotic circle of Willis which is often anomalous in more than 50% of the normal adult brains. These anomalies increase the risk of the stroke and transient ischemic attack in older patients. Adequate blood flow through the circle of Willis is often necessary to prevent these ischemic infarctions. The anomalies of cerebral vessels are directly related to the differential growth of various parts of the brain. A detailed knowledge of the individual measurements of the cerebral arteries is useful to neurosurgeon in planning the shunt operations and in the choice of their patients. The present study is aimed to analyze the average dimensions of the vessels at the base of brain and an attempt to explain the common form of variations in terms of embryological development. Materials and methods: Fifty adult cadaveric brains were obtained from routine cadaveric dissections. The base of the brain with the circle of Willis was fixed in 10% formalin and preserved. The circle was analyzed for variations in the size, length and number of the component vessels and any asymmetry in the configuration. The dimensions of the vessels forming the circle were measured using graduated calipers. The observations were recorded and tabulated. Results: Asymmetry was observed in 10% to 36% of the circles in this study. Anomalies were more common in the posterior than in the anterior part of the circle. The posterior anomalies included hypoplastic vessels, absent vessels and embryonic derivation while anterior anomalies were predominantly of accessory vessels. Middle cerebral artery exhibited the least variations. In majority of the circles, left sided vessels were larger in diameter than the right. Conclusions: Variations are more common in the posterior than in the anterior part of the circle and on the right than on the left side of the brain. There was no correlation between the variations of circle of Willis of the right side and the left cerebral dominance. There seems to be no difference between races, concerning the anatomic variations of the brain circulation.

Bifurcation geometry and the presence of cerebral artery aneurysms

2004 ◽  
Vol 101 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Tor Ingebrigtsen ◽  
Michael K. Morgan ◽  
Ken Faulder ◽  
Linda Ingebrigtsen ◽  
Trygve Sparr ◽  
...  
Keyword(s):  
Cerebral Artery ◽  
Geometric Model ◽  
Cerebral Arteries ◽  
Multivariate Logistic Regression Analysis ◽  
Circle Of Willis ◽  
Parent Vessel ◽  
Content Type ◽  
Optimality Principles ◽  
The Relationship ◽  
Fine Print

Object. The angles of arterial bifurcations are governed by principles of work minimization (optimality principle). This determines the relationship between the angle of a bifurcation and the radii of the vessels. Nevertheless, the model is predicated on an absence of significant communication between these branches. The circle of Willis changes this relationship because the vessels proximal to the ring of vessels have additional factors that determine work minimization compared with more distal branches. This must have an impact on understanding of the relationship between shear stress and aneurysm formation. The authors hypothesized that normal bifurcations of cerebral arteries beyond the circle of Willis would follow optimality principles of minimum work and that the presence of aneurysms would be associated with deviations from optimum bifurcation geometry. Nevertheless, the vessels participating in (or immediately proximal to) the circle of Willis may not follow the geometric model as it is generally applied and this must also be investigated. Methods. One hundred seven bifurcations of the middle cerebral artery (MCA), distal internal carotid artery (ICA), and basilar artery (BA) were studied in 55 patients. The authors analyzed three-dimensional reconstructions of digital subtraction angiography images with respect to vessel radii and bifurcation angles. The junction exponent (that is, a calculated measure of the division of flow at the bifurcation) and the difference between the predicted optimal and observed branch angles were used as measures of deviation from the geometry thought best to minimize work. The mean junction exponent for MCA bifurcations was 2.9 ± 1.2 (mean ± standard deviation [SD]), which is close to the theoretical optimum of 3, but it was significantly smaller (p < 0.001; 1.7 ± 0.8, mean ± SD) for distal ICA bifurcations. In a multilevel multivariate logistic regression analysis, only the observed branch angles were significant independent predictors for the presence of an aneurysm. The odds ratio (OR) (95% confidence interval) for the presence of an aneurysm was 3.46 (1.02–11.74) between the lowest and highest tertile of the observed angle between the parent vessel and the largest branch. The corresponding OR for the smallest branch was 48.06 (9.7–238.2). Conclusions. The bifurcation beyond the circle of Willis (that is, the MCA) closely approximated optimality principles, whereas the bifurcations within the circle of Willis (that is, the distal ICA and BA) did not. This indicates that the confluence of hemodynamic forces plays an important role in the distribution of work at bifurcations within the circle of Willis. In addition, the observed branch angles were predictors for the presence of aneurysms.

scholarly journals Anatomical variations of circle of Willis - a cadaveric study

2017 ◽  
Vol 4 (4) ◽  
pp. 1249 ◽  
Author(s):  
Ramanuj Singh ◽  
Ajay Babu Kannabathula ◽  
Himadri Sunam ◽  
Debajani Deka
Keyword(s):  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Anterior Part ◽  
Cerebral Arteries ◽  
Anatomical Variations ◽  
Circle Of Willis ◽  
Anterior Communicating Artery ◽  
Surgical Interventions ◽  
Collateral Channel ◽  
The Right

Background: The circle of Willis (CW) is a vascular network formed at the base of skull in the interpeduncular fossa. Its anterior part is formed by the anterior cerebral artery, from either side. Anterior communicating artery connects the right and left anterior cerebral arteries. Posteriorly, the basilar artery divides into right and left posterior cerebral arteries and each join to ipsilateral internal carotid artery through a posterior communicating artery. Anterior communicating artery and posterior communicating arteries are important component of circle of Willis, acts as collateral channel to stabilize blood flow. In the present study, anatomical variations in the circle of Willis were noted.Methods: 75 apparently normal formalin fixed brain specimens were collected from human cadavers. 55 Normal anatomical pattern and 20 variations of circle of Willis were studied. The Circles of Willis arteries were then colored, photographed, numbered and the abnormalities, if any, were noted.Results: Twenty variations were noted. The most common variation observed is in the anterior communicating artery followed by some other variations like the Posterior communicating arteries, Anterior cerebral artery and posterior cerebral artery (PCA) was found in 20 specimens.Conclusions: Knowledge on of variations in the formation of Circle of Willis, all surgical interventions should be preceded by angiography. Awareness of these anatomical variations is important in the neurovascular procedures.

MODELING REDISTRIBUTION CEREBRAL CIRCULATION

2021 ◽  
Vol 1 (4) ◽  
pp. 13-18
Author(s):  
Vladislav Nikolaevich Nikitin ◽  
◽  
Ekaterina Valerevna Kozhemyakina ◽  
Keyword(s):  
Blood Flow ◽  
Internal Carotid ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Entire Body ◽  
Compensatory Mechanisms ◽  
Vertebral Arteries ◽  
The Central Nervous System ◽  
Flow Through ◽  
The Brain

The brain is one of the most important organs responsible for the health and functioning of the entire body. The blood supply to the brain is carried out through 2 internal carotid and 2 vertebral arteries in norm. The brain, like other body systems, has protective (compensatory) mechanisms aimed at maintaining the necessary blood flow, one of which is the circle of Willis. The article proposes a mechanism for how blood flow is redistributed through the arteries feeding the brain, which is based on the assumption that the central nervous system controls in such a way that it minimizes flows through the connective arteries of the circle of Willis, the flows along which are normal (with symmetry of the left and right sides) practically equal to zero. Сase of the structure of the circle of Willis is considered in norm. The indicated redistribution mechanism is still only the first step towards an attempt to predict cases of changes in blood flow through the cerebral arteries, especially in stroke. In further works, it is planned to consider the inverse problem, i.e. determine the flows through the internal carotid and vertebral arteries, provided that the flows through the cerebral arteries extending from the circle of Willis have normal flow values.

Wall Shear Stress and Gradient at Anterior Communicating Artery in Pulsating Flow

2000 ◽  
Author(s):  
Ryuhei Yamaguchi ◽  
Susumu Kudo ◽  
Hiroyuki Yamanobe ◽  
Mikio Nakajima ◽  
Hiroshi Ujiie
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Artery ◽  
Major Part ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Pulsating Flow ◽  
Anterior Communicating Artery ◽  
Wall Shear

Abstract The aneurysm in the cerebral artery is apt to initiate around the “Circle of Willis”. The anterior communicating artery (ACoA), which composes one of major part of the circle of Willis, is the most predilection artery of the aneurysm. This artery is characterized by a singular geometry. At this artery, two proximal anterior cerebral arteries (A1, confluence) join facing each other. Just at this artery, the flow bifurcates two distal anterior cerebral arteries (A2, bifurcation). Namely, this artery has a function as a bypass channel. Therefore, the flow around the anterior communicating artery would be very unstable. The aneurysm arises around the apex of this artery where the confluent flow collides.

An Experimental Study of the Effects Anatomical Variations Have on Collateral Flows Within the Circle of Willis

2011 ◽  
Author(s):  
Paul Fahy ◽  
Patrick Delassus ◽  
Padraig O’Flynn ◽  
Liam Morris
Keyword(s):  
Experimental Study ◽  
Blood Flow ◽  
Cerebral Arteries ◽  
Anatomical Variations ◽  
Flow Patterns ◽  
Circle Of Willis ◽  
Collateral Flow ◽  
Arterial Network ◽  
Flow Feature ◽  
The Brain

The circle of Willis (CoW) is a complex arterial network comprising of major cerebral arteries that converge to form a pentagonal arrangement as shown in Figure 1(A). This arterial network supplies oxygen-enriched blood to the brain. An incomplete CoW can exist in up to 50% of cases [1]. These missing vessels can be accommodated by the collateral flow feature within the CoW configuration. In certain circumstances, anatomical variations within the CoW can result in undesirable flow patterns [2–3]. It is unclear from the literature what effects these variations can have on blood flow collision paths within a complete CoW.

scholarly journals Distribution of serotonin-like immunoreactive nerves in major cerebral arteries of rabbit: an immunohistochemical study.

1989 ◽  
Vol 37 (9) ◽  
pp. 1383-1386 ◽  
Author(s):  
U Dhall ◽  
G Burnstock
Keyword(s):  
Immunohistochemical Study ◽  
Anterior Part ◽  
Cerebral Arteries ◽  
Posterior Part ◽  
Nerve Fibers ◽  
Circle Of Willis ◽  
Immunofluorescence Technique ◽  
Whole Mount ◽  
Peptidergic Innervation ◽  
Indirect Immunofluorescence Technique

We studied the distribution pattern of serotonin-like immunoreactive nerve fibers in the major cerebral vessels of rabbit by an indirect immunofluorescence technique using whole-mount stretch preparations. The density of serotonin-like immunoreactive nerve fibers was greater in vessels of the posterior part of the circle of Willis compared with that in the anterior part. This is in contrast to most of the observations reported previously regarding adrenergic, cholinergic, and peptidergic innervation of the circle of Willis.

Sign in / Sign up

Export Citation Format

Share Document