Bridging veins (BVs) drain the blood from the cerebral cortex into dural sinuses. BVs have one end attached to the brain and the other to the superior sagittal sinus (SSS), which is attached to the skull. Relative movement between these two structures can cause BV to rupture producing acute subdural haematoma, a head injury with a mortality rate between 30 and 90%. A clear understanding of the BVs microstructure is required to increase the biofidelity of BV models when simulating head impacts. Twelve fresh BV samples draining in the superior sagittal sinus (SSS) from a single human cadaver were cut open along their length and placed on an inverted multiphoton microscope. To ensure that the BVs were aligned with the axial direction an in-house built, uniaxial tension set-up was used. Two scans were performed per sample. Before the first scan, a minor displacement was applied to align the tissue; then, a second scan was taken applying 50% strain. Each BV was scanned for a length of 5 mm starting from the drainage site into the SSS. Imaging was performed on a Zeiss LSM780 microscope with an 25\(\times\) water immersion objective (NA 0.8), coupled to a tunable MaiTai DS (Spectraphysics) pulsed laser with the wavelength set at 850 nm. Second harmonic and fluorescence signals were captured in forward and backward direction on binary GaAsP (BiG) detectors and stored as four colour Z-stacks. Prior to the calculation of the local orientations, acquired Z-stacks were denoised and enhanced to highlight fibrillar structures from the background. Then, for each Z-plane of the stack, the ImageJ plugin OrientationJ was used to extract the local 2D orientations of the fibres based on structure tensors. Two kinds of collagen architectures were seen. The most common (8\(/\)12 samples) was single layered and had a uniform distribution of collagen. The less common (4\(/\)12 samples) had 2 layers and 7 to 34 times thicker collagen bundles on the outer layer. Fibre angle analysis showed that collagen was oriented mainly along the axial direction of the vessel. The von Mises fittings showed that in order to describe the fibre distribution 3 components were needed with mean angles \(\mu\) at \(-\) 0.35, 0.21, \(-\) 0.02 rad or \(-\) 20.2\(^{\circ }\), 12.1\(^{\circ }\), \(-\) 1.2\(^{\circ }\) relative to the vessel’s axial direction which was also the horizontal scan direction.

桥静脉 (BV) 将血液从大脑皮层排入硬脑膜窦。BV 的一端连接到大脑，另一端连接到与颅骨相连的上矢状窦 (SSS)。这两个结构之间的相对运动会导致 BV 破裂，产生急性硬膜下血肿，这是一种死亡率在 30% 到 90% 之间的头部损伤。在模拟头部撞击时，需要清楚地了解 BV 的微观结构，以提高 BV 模型的生物保真度。在上矢状窦 (SSS) 中从单个人类尸体引流的 12 个新鲜 BV 样本沿其长度切开并放置在倒置多光子显微镜上。为确保 BV 与轴向对齐，使用了内部构建的单轴张力设置。每个样品进行两次扫描。在第一次扫描之前，应用微小的位移来对齐组织；然后，施加 50% 应变进行第二次扫描。每个 BV 从引流部位开始扫描到 SSS 的长度为 5 毫米。成像是在蔡司 LSM780 显微镜上进行的，具有 25\(\times\)水浸物镜 (NA 0.8)，耦合到波长设置为 850 nm 的可调 MaiTai DS（光谱物理）脉冲激光器。二次谐波和荧光信号在二元 GaAsP (BiG) 检测器上向前和向后捕获，并存储为四色 Z 堆栈。在计算局部方向之前，对获得的 Z 堆栈进行去噪和增强，以突出背景中的纤维状结构。然后，对于堆栈的每个Z平面，ImageJ 插件 OrientationJ 用于基于结构张量提取纤维的局部 2D 方向。观察到两种胶原结构。最常见的（8 \(/\) 12 个样品）是单层的，并且具有均匀分布的胶原蛋白。较不常见的 (4\(/\) 12 个样品）在外层有 2 层和 7 到 34 倍厚的胶原束。纤维角度分析表明，胶原蛋白主要沿血管轴向取向。von Mises 拟合表明，为了描述纤维分布，需要 3 个分量的平均角\(\mu\)在\(-\) 0.35、0.21、\(-\) 0.02 rad 或\(-\) 20.2 \(^{\circ }\) , 12.1 \(^{\circ }\) , \(-\) 1.2 \(^{\circ }\)相对于容器的轴向，也是水平扫描方向。