Abstract：
The arterial circle of Willis is a well-known and interconnecting set of blood vessels at the base of the brain. However, its lesser-known venous counterpart, the circle of Trolard, has had almost no attention in the extant medical literature.
Twenty-four adult human brains underwent dissection of the circle of Trolard. When identified, its component vessels and relationships with adjacent structures were confirmed and documented with photography and measured using microcalipers.
A complete circle of Trolard was identified on 42% of specimens. Most (64%) incomplete circles were incomplete anteriorly with no anterior communicating vein. The anterior communicating veins joined the anterior cerebral veins superior to the optic chiasm and continued posteriorly. The anterior communicating veins had a mean diameter of 0.45 mm. The length of these veins ranged from 0.8 mm to 1.45 mm. Thirty-six percent of circles were incomplete posteriorly with lack of a posterior communicating vein. The posterior communicating veins were always larger and longer than the anterior cerebral veins. The posterior communicating veins had a mean diameter of 0.8 mm. The length of these veins ranged from 2.8 to 3.9 cm. In general, the circles of Trolard were more or less symmetrical. However, in 2 specimens, asymmetry existed.
A better understanding of the venous circle of Trolard might decrease iatrogenic injury during approaches to the base of the brain and improve diagnoses based on imaging of the skull base. To our knowledge, this is the first anatomical study dedicated to the circle of Trolard.
Twenty-four adult human brains underwent dissection of the circle of Trolard. When identified, its component vessels and relationships with adjacent structures were confirmed and documented with photography and measured using microcalipers.
A complete circle of Trolard was identified on 42% of specimens. Most (64%) incomplete circles were incomplete anteriorly with no anterior communicating vein. The anterior communicating veins joined the anterior cerebral veins superior to the optic chiasm and continued posteriorly. The anterior communicating veins had a mean diameter of 0.45 mm. The length of these veins ranged from 0.8 mm to 1.45 mm. Thirty-six percent of circles were incomplete posteriorly with lack of a posterior communicating vein. The posterior communicating veins were always larger and longer than the anterior cerebral veins. The posterior communicating veins had a mean diameter of 0.8 mm. The length of these veins ranged from 2.8 to 3.9 cm. In general, the circles of Trolard were more or less symmetrical. However, in 2 specimens, asymmetry existed.
A better understanding of the venous circle of Trolard might decrease iatrogenic injury during approaches to the base of the brain and improve diagnoses based on imaging of the skull base. To our knowledge, this is the first anatomical study dedicated to the circle of Trolard.
摘要：
背景：Willis的动脉环是大脑底部的一组众所周知的相互连接的血管。然而,它鲜为人知的静脉对应物，Trolard的圆圈，在现有的医学文献中几乎没有受到关注。
方法：对24个成年人的大脑进行了Trolard环的解剖。当被识别时，其组成血管以及与相邻结构的关系通过摄影和使用显微卡尺进行了确认和记录。
结果：在42％的样本上鉴定出完整的Trolard环。大多数（64％）不完整的圆圈前部不完整，没有前交通静脉。前交通静脉与视神经交叉上方的大脑前静脉相连，并向后继续。前交通静脉的平均直径为0.45mm。这些静脉的长度范围为0.8mm至1.45mm。36％的圆圈向后不完整，缺乏后交通静脉。后交通静脉总是比大脑前静脉更大，更长。后交通静脉的平均直径为0.8mm。这些静脉的长度范围为2.8至3.9厘米。总的来说,Trolard的圆圈或多或少是对称的。然而,在2个标本中，不对称存在。
结论：更好地了解Trolard的静脉环可能会减少进入脑底部的过程中的医源性损伤，并改善基于颅底成像的诊断。据我们所知,这是第一个致力于Trolard圆的解剖学研究。
方法：对24个成年人的大脑进行了Trolard环的解剖。当被识别时，其组成血管以及与相邻结构的关系通过摄影和使用显微卡尺进行了确认和记录。
结果：在42％的样本上鉴定出完整的Trolard环。大多数（64％）不完整的圆圈前部不完整，没有前交通静脉。前交通静脉与视神经交叉上方的大脑前静脉相连，并向后继续。前交通静脉的平均直径为0.45mm。这些静脉的长度范围为0.8mm至1.45mm。36％的圆圈向后不完整，缺乏后交通静脉。后交通静脉总是比大脑前静脉更大，更长。后交通静脉的平均直径为0.8mm。这些静脉的长度范围为2.8至3.9厘米。总的来说,Trolard的圆圈或多或少是对称的。然而,在2个标本中，不对称存在。
结论：更好地了解Trolard的静脉环可能会减少进入脑底部的过程中的医源性损伤，并改善基于颅底成像的诊断。据我们所知,这是第一个致力于Trolard圆的解剖学研究。
