MRI Measurements Of The Rectus Capitis Posterior Minor In Healthy Adults

Objectives.The rectus capitis posterior minor(RCPmi),which exists in the innermost part of the suboccipital muscle group,is of vital importance in physiological functions.The concept of the myodural bridge(MDB)was first proposed by Hack in 1995,which was defined as the dense connective tissue extending from the RCPmi to the dura mater through the posterior membrane of the atlanto-occipital joint.Some clinical studies found that diseased RCPmi and the MDB may be closely related to chronic cervical headaches pathologically.However,there has been no report of the morphology data of healthy adults’ RCPmi.Therefore,the purpose of this study was to explore the healthy anatomical parameters of RCPmi using the magnetic resonance images(MRI)and provide a imaging reference of the length and area of RCPmi,and then to provide a reference for an anatomical,physiological and pathological study of the RCPmi.Materials and Methods.1.The head and neck of 10 specimens was firstly dissected gross anatomically and then the skin and muscle were removed sequentially by layers until the deepest RCPmi was exposed.Thus,the related data of RCPmi in 20 sides was measured.2.According to the results of anatomical measurement,The l09 subjects were imaged by T2-weighted scanning with seven kinds of scanning angles separately,including 0,25,30,35,40,45,and 50 degrees.The length of RCPmi in healthy adults in each angle was measured by MR workstation and the data was statistically analyzed,which shows that the scanning angle with the longest RCPmi was set as the optimum scanning angle.The area of RCPmi in this T2-weighted image was measured as the reference of the area of the left RCPmi in healthy adults by using Mimics software.At last,the gander differences and the aging changes were also statistically analyzed.In order to explore aging changes,the 109 subjects were divided into two age groups respectively in male and female,namely,above 45 years old and below 45 years old(including 45 years old)and the data was statistically analyzed accordingly.Based on the statistical analysis,the length and area of RCPmi have a significant gender difference(p<0.05),but there were no aging changes.That is to say,RCPmi doesn’t change as the age goes.Conclusion.RCPmi,which exists in the innermost part of the suboccipital muscle group,plays an important role both physiologically and pathologically.This study provided MRI scanning method and the imaging reference for the related basic and clinical medicine studies of RCPmi.