丽纹攀蜥肌硬膜桥的存在及形态学特征

Existence and morphology features of the myodural bridge in JapaLura Splendida

目的人肌硬膜桥为枕下头后小直肌、头后大直肌、头下斜肌及项韧带等与硬脊膜之间的致密纤维连接结构,具有重要的生理作用及临床意义。已有研究提出肌硬膜桥可能与脑脊液循环和慢性颈源性头痛有关。目前研究发现,哺乳动物中普遍存在肌硬膜桥这一结构,并且鸟类中的家鸡、岩鸽,爬行纲中的暹罗鳄、巴西龟都存在肌硬膜桥样结构。为进一步分析肌硬膜桥在不同纲目的结构形态差异,为其功能研究提供基础。本次研究以爬行纲蜥蜴目中最常见的丽纹攀蜥为实验对象,补充爬行纲肌硬膜桥的形态特点。方法采用大体解剖、厚断层切片、组织学切片染色等方法,对20只丽纹攀蜥的枕后区结构特点及肌硬膜桥样结构的存在情况进行观察。结果丽纹攀蜥枕后肌由融合的头背大直肌、头背小直肌、头前斜肌(我们定义为头背直肌)及头后斜肌构成。于寰枕间隙内,自头背直肌腹侧发出的片状致密纤维连接组织向腹侧走行,与硬脊膜紧密相连。于寰枢间隙内,自头后斜肌腹侧发出的致密纤维连接组织向腹侧走行,与硬脊膜紧密相连。且此致密纤维连接结构为具有极强双折光性的Ⅰ型胶原纤维。结论丽纹攀蜥的头背直肌、头后斜肌与硬脊膜之间存在致密的纤维连接结构,即肌硬膜桥样结构。此结构可能与丽纹攀蜥头颈部的活动密切相关,发挥与人类肌硬膜桥相似的生理功能。

Objective The dense fibrous connective tissue that connects sub-occipital muscles which consist of the rectus capitis posterior minor muscle(RCPmi),rectus capitis posterior major muscle(RCPma),obliquus capitis inferior muscle(OCI)and nuchal ligament(NL)to the spinal dura mater(SDM),is described as the myodural bridge(MDB)in humans.The MDB is perceived as an essential anatomical structure and has been a subject of interest for clinicians.Studies have revealed that MDB may be related to the dynamic circulation of the cerebrospinal fluid(CSF)and a chronic cervicogenic headache.To date,the MDB is identified as a universal,existing structure in mammals and it exists in other vertebrates as well,such as Gallus domesticus and Rock pigeons in Avifauna,Siamese crocodile and Trachemys scripta elegans in Reptile.The current study is to further analyze different structures features of the MDB in sundry classes and provide the anatomical basis for functional studies.The JapaLura Splendida is the most common species in Lacertiformes,Reptilia.So we chose it as the experimental object to supply the morphological study of the MDB in Reptilia.Methods The study was based on gross anatomical dissection,thick sheet section,histological staining to observe the structural characteristics of the post-occipital area of twenty JapaLura Splendidas and the existence of the MDB.Results The deep post-occipital muscles were composed of the rectus capitis dorsal muscle(RCD)and the obliquus capital posterior(OCP)muscle.The RCD was merged by the rectus capitis dorsal major muscle(RCDma),the rectus capitis dorsal minor muscle(RCDmi)and the obliquus capitis anterior muscle(OCA).In the atlanto-occipital space,the dense fibrous bundles were found to originate from the ventral aspect of the RCD and run ventral,closely inserting into the SDM.In the atlanto-axial space,the dense fibrous bundles were found to originate from the ventral aspect of the OCP and run ventral,closely contacted with the SDM.These dense fibrous bundles were the collagen type I fibers with strong double refraction.Conclusion The result of this study indicates that the MDB is located between the post-occipital muscles and the SDM in JapaLura Splendida.The MDB of Japalura splendida may be related to the activities of the head and neck,and exert a physiological function similar to the MDB in humans.