Hildebrand C, Oqvist G, Brax L, Tuisku F
Department of Cell Biology, University of Linköping, Sweden.
Anat Rec. 1991 Apr;229(4):545-55. doi: 10.1002/ar.1092290415.
Several recent reports discuss the role of joint nerves in arthritis. Many of these are based on studies in the rat. The aim of this study is to examine the anatomy of the rat knee joint, in search for a primary articular nerve, and to analyze the fibre composition of that nerve. The results show that the structure of the joint differs in some respects from the human knee. At the upper end of the bony patella a cartilaginous patella extends proximally, forming the anterior wall of the suprapatellar bursa. Distinct collateral ligaments are integrated in the joint capsule. The extensor digitorum longus muscle bridges the knee joint, originating from the lateral femoral epicondyle. The well-developed menisci contain pyramid-shaped ossicles. The cruciate ligaments are arranged like in the human knee. A large posterior (PAN) and a small medial (MAN) articular nerve can be identified. The PAN is composed of some 400 axons, about 80% of which are unmyelinated. All myelinated fibres are sensory. They present a unimodal size spectrum with a size range of 1-8 microns, and a predominance of small fibres. Specific denervations indicate that about 1/3 of the unmyelinated axons represent afferents, and some 2/3 are sympathetic efferents. Interestingly, neonatal capsaicin treatment did not influence the number of unmyelinated PAN axons. The functional significance of the numerous unmyelinated sympathetic and sensory PAN axons in the normal knee joint remains to be elucidated.
最近的几份报告讨论了关节神经在关节炎中的作用。其中许多报告基于对大鼠的研究。本研究的目的是检查大鼠膝关节的解剖结构，寻找主要的关节神经，并分析该神经的纤维组成。结果表明，该关节的结构在某些方面与人类膝关节不同。在髌骨上端，一块软骨性髌骨向近端延伸，形成髌上囊的前壁。明显的侧副韧带融入关节囊。趾长伸肌跨过膝关节，起自股骨外侧髁。发育良好的半月板含有金字塔形小骨。交叉韧带的排列与人类膝关节相似。可以识别出一条大的后关节神经（PAN）和一条小的内侧关节神经（MAN）。PAN由约400条轴突组成，其中约80%为无髓鞘轴突。所有有髓鞘纤维都是感觉性的。它们呈现出单峰大小谱，大小范围为1-8微米，且以小纤维为主。特定的去神经支配表明，约1/3的无髓鞘轴突为传入神经，约2/3为交感传出神经。有趣的是，新生大鼠辣椒素处理并未影响无髓鞘PAN轴突的数量。正常膝关节中大量无髓鞘交感和感觉PAN轴突的功能意义仍有待阐明。
