Anatomical Research For Rectus Capitis Posterior Minor Muscle By P45Plastination Technology

Objective.Myodural bridge was firstly described by Gary D. Hack in1995, whichwas thought related with the chronic cervicogenic headache. A review ofthe literatures reveals that few reports describing the detailed terminaltypes of rectus capitis posterior minor muscle(RCPmi). In this study, P45plastination technology and anatomical dissection were performed on19head specimens，to describe and define the different types of the terminalregions of the rectus capitis posterior minor muscle.Methods.This study used P45plastination technology in14cadavers and grossanatomical dissection in5cadavers.Results.1. Observation from P45plastination technologyThis study demonstrated that the rectus capitis posterior minor muscle were terminated at three different regions, including the posterioratlanto-occipital interspace, posterior arch of atlas, posterior atlanto-axialinterspace.Type I：The tendon of RCPmi terminated in only posterior arch of atlas.The ratio of type I is7.1％（1/14）;Type Ⅱ: The tendon of RCPmi terminated in both the posterioratlanto-occipital interspace and posterior arch of atlas. The ratio of typeII was42.9％（6/14）；Type Ⅲ: The tendon of RCPmi terminated in the posterior arch of atlasand posterior atlanto-axial interspace. The ratio of type III was7.1％（1/14）；Type Ⅳ: The tendon of RCPmi terminated in not only the posterioratlanto-occipital interspace, posterior arch of atlas, but also the posterioratlanto-axial interspace. The ratio of type IV was42.9％（6/14）.2. Observation from anatomical dissectionIn the5specimens, the tendon of RCPmi was all firmly terminated to theposterior arch of atlas. In2of the5specimens, the RCPmi was alsoterminated to the posterior atlanto-axial interspace and the dense tendonwas fused to the dorsal cervical spinal dura(type III). In1of the5specimens, it was observed that the RCPmi was attached to the posterioratlanto-occipital interspace (type II). Conclusion.Different termination pattern of the rectus capitis posterior minor musclewere found in present study. It was speculated that this muscle, togetherwith others in suboccipital area, might be an important source of the forcefor the circulation of CSF.