Objective The aim of this study was to investigate functional anatomy of the craniolateral bundle (CrLB) and caudomedial bundle (CdMB) of caudal cruciate ligament in normal Beagles.

Materials and Methods Twelve stifle joints of 12 Beagle cadavers that were euthanatized for reasons other than musculoskeletal disease were used. Anatomical characteristics of femoral and tibial attachment regions of the caudal cruciate ligament were described, and location and area of the footprints of the CrLB and CdMB were objectively determined. The CrLB was artificially divided into two equal fibre bundle units and the CdMB was artificially divided into four equal bundle units. Changes in the fibre arrangement were recorded during stifle range of motion, and the tension of each fibre bundle unit at various stifle joint angles was objectively measured.

Results The CrLB was attached to the intercondylar fossa of the femur, and the CdMB was attached to the medial surface of the medial condyle of the femur. The centre of the CrLB attachment site was located craniomedial to that of the CdMB on the tibia. During stifle range of motion, each divided fibre bundle unit in the CrLB and CdMB was twisted externally. The tension of entire CdMB tended to be higher than that of entire CrLB at 180 to 135 degrees of the stifle angles. In full extension angle, the tension of entire CdMB was 1.55 times higher than that of entire CrLB.

Clinical Significance This study contributes to understanding of the biomechanics and the function of the caudal cruciate ligament, which help to elucidate the pathophysiology of caudal cruciate ligament tear and to develop stifle joint stabilization surgery.

目的 本研究的目的是研究正常比格犬尾交叉韧带的颅外侧束（CrLB）和尾内侧束（CdMB）的功能解剖。

材料和方法 使用 了因肌肉骨骼疾病以外的原因被安乐死的 12 具比格犬尸体的 12 个膝关节。描述了尾交叉韧带的股骨和胫骨附着区的解剖特征，并客观地确定了 CrLB 和 CdMB 足迹的位置和面积。CrLB 被人为地分成两个相等的纤维束单元，CdMB 被人为地分成四个相等的纤维束单元。在膝关节运动范围内记录了纤维排列的变化，并客观地测量了各个纤维束单元在不同膝关节角度下的张力。

结果 CrLB附着于股骨髁间窝，CdMB附着于股骨内侧髁内表面。CrLB 附着点的中心位于胫骨上 CdMB 的颅内侧。在膝关节运动范围内，CrLB 和 CdMB 中每个分开的纤维束单元都在外部扭曲。在 180 到 135 度的扼杀角处，整个 CdMB 的张力往往高于整个 CrLB 的张力。在全伸展角下，整个 CdMB 的张力比整个 CrLB 的张力高 1.55 倍。

临床意义 本研究有助于了解尾十字韧带的生物力学和功能，有助于阐明尾十字韧带撕裂的病理生理学，发展膝关节稳定手术。