A morphological study on the circle of Willis in the dog.
نویسنده
چکیده
The structure and variations of the circle of Willis in 55 days were studied from corrosion-cast specimens. The perivascular sympathetic innervation of the circle was also investigated in 9 dogs using the Schultz silver impregnation method. The following results were obtained. 1) The circle was entirely closed in all specimens. 2) The basic shape and variations of the circle were briefly as follows. (i) The connected shape of the bilateral anterior cerebral arteries could be classified into three types?having a common trunk (87.3%) , having a single anterior communicating artery (9.1%) and having a double anterior communicating artery (3.6%). (ii) Asymmetry of the diameter of the anterior cerebral artery was found in 14.5%. (iii) Button-hole formation was observed in 1 case (1.8%) in the posterior part of the circle on each side. 3) The patterns of divergence of the main cerebral arteries which arose from the circle were as follows. (i) The divergent patterns of the internal carotid artery could be classified into five types. The most general was a pattern which first gave off the posterior communicating artery, and secondly divided into the middle and anterior cerebral arteries. Such cases were found in 85.5% on the right side and 81.8% on the left. (ii) The position of origin of the anterior choroidal artery was from any of three arteries-the middle cerebral (right: 69.1%, left: 67.3%), the posterior communicating (right: 20.0%, left: 23.6%) and the internal carotid artery (right: 10.9%, left: 9.1%). (iii) Double posterior cerebral and anterior: cerebellar arteries were found in 1.8% on the left side for the former and in 1.8% on each side for the latter. 4) The diameters of the main cerebral arteries were measured in 50 dogs and a comparison was made of the diameters of the vessels on the right side with those on the left. In the dog, the diameter of the terminal branch of the basilar artery was slightly larger than that of the posterior communicating artery in 86.0% on the riright side and 94.0% on the left. 5) A correlation existed between the diameter of the posterior cerebral artery and that of the posterior communicating artery, and between the diameter of the pasterior cerebral artery and that of the terminal branch of the basilar artery. 6) The posterior cerebral artery was found to be innervated not by the sympa-
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عنوان ژورنال:
- Okajimas folia anatomica Japonica
دوره 58 3 شماره
صفحات -
تاریخ انتشار 1981