Oljective. To investigate the morphological properties of pig cerebral bridging vein. Methods. The morphology and fibre arrangement of 15 cerebral bridging veins obtained from 7 Danish Yorkshire landrace pigs were observed. Results There was a narrow region at the junction of the cerebral bridging veins and superior sagittal sinus termed "outflow cuff segment". The diameter and length of outflow ctff segment were much smaller and the thickness was higher than those of the cerebral bridging veins (P<0.01), and circumferential coltagen fibres were most dense in the outflow cuff segment. The opening angle of the outflow cuff segment and the cerebral bridging veins were 115+4 and 120+4(P>0.05). Conclusions. There were differences in fibre arrangement and morphological properties between the outflow cuff segment and the cerebral bridging vein, just like a resistance valve, the outflow cuff segment may play an important role in stabilizing cerebral venous outflow and regulating intracranial pressure.

目的 研究正常和过度换气时脑桥静脉对颅内压增高的血流动力学改变。方法 选择7头丹麦白约克猪，通过向枕大池灌注人工脑脊液，逐步增加颅内压，从基础值（大约1.3k pa）到2.7kpa和4.0kpa，用彩色超声多谱勒测量正常和过度换气状态下，颅内压增高对于脑桥静脉的血流速度、直径和脉冲指数的影响。结果 随着颅内压增高，脑桥静脉的血流速度减慢，直径和脉冲指数增加，而颅内压增高对中心静脉压、动脉CO2分压、平均动脉压无明显影响。结论 脑静脉容量可以被认为是颅内容量缓冲剂，收缩脑静脉将为降低颅内压提供一条新的治疗途径。

目的 研究颅脑桥静脉在不同应力状态下的被动调节机制与其生物力学特性之间的关系。方法 对15 条颅脑桥静脉进行充压实验，计算其在不同压力范围下的轴向及周向应力 应变关系。结果 流出口狭部的直径及长度较颅脑桥静脉的小，周向的应力 应变曲线表明颅脑桥静脉流出口狭部在周向上其硬度明显高于桥静脉。在轴向上比较应力 应变特性时，桥静脉的硬度明显高于桥静脉流出口狭部。结论 桥静脉流出口狭部与桥静脉之间的生物力学特性存在差异，它作为一个功能性限流阻力阀，在稳定脑静脉血流中起关键作用。

f region. The diameter was smaller in the outflow cuff segment than in the cerebral bridging veins in the pressure range studied (0-23 mm Hg) whereas the thickness was highest in the outflow cuff segment (p＜0.01)＝The circumferential stress-strain analysis showed that the outflow cuff segment was extensible up to a strain of 0.25. At higher strains the outflow cuff segment was progressively stifferthan the cerebral bridging vein (p＜0.05)＝The longitudinal stress-strain relation for the cerebral bridging vein was shifted to the left compared to the outflow cuff segment (p＜0.05)＝When compared to the stress-strain properties in the circumferential direction, the outflow cuff segment was more extensible and the cerebral bridging vein stiffer in longitudinal direction (p＜0.05)＝The opening angle of the outflow cuff segment and the cerebral bridging vein was 115 B 4 and 120 B 4 (means B SE) without statistical difference between the two regions. In conclusion the difference in biomechanical properties between the outflow cuff segment and the cerebral bridging vein was associated to their difference in histology and fibre arrangement. This indicates that the function of the outflow cuff segment is to act as a flow-limiting resistance to the outflow from the cerebral circulation.