| Background and objective:With the continuous development of spinal endoscopy and the innovation of endoscopic dynamic system,the minimally invasive spinal technique represented by transforaminal endoscopy has developed rapidly.In recent years,the indications for transforaminal endoscopy have been expanding from cervical and lumbar diseases to thoracic diseases.With the development of thoracic transforaminal technique,a series of complications have followed.Therefore,the anatomical structure of the thoracic foramen has been paid more and more attention by scholars.The anatomical characteristics and clinical significance of the internal and external ligaments of the thoracic foramen have been discussed in previous studies,but the research concerned with the extraforaminal arteries in the thoracic foramen is rare.This study is an anatomical study about the extraforaminal arteries in the thoracic foramen,fully reveals the characteristics of the regional artery,establish and perfect relevant theoretical system,and discusses its significance in clinical application,so as to provide a more detailed anatomic data for clinical doctors,thereby reducing the surgery complications of the thoracic transforaminal endoscopic surgery.By this means,hope to make contributions to the follow-up development of thoracic transforaminal endoscopic technology.Methods:We studied the anatomy of 154 thoracic intervertebral foramen from 7 specimens.The origin,number,course and distribution of branches of thoracic extraforaminal arteries and their relationship with nerve root location were observed and recorded.The diameter of all arterial branches was measured by measuring the outer diameter at the beginning of each artery.The data were repeated twice and the average value was taken for statistical analysis,and the distribution of the thoracic extraforaminal arteries was analyzed.Results:According to the different types of first-order branching,they could be divided into 4 types:Ⅰ,Ⅱ,Ⅲ and Ⅳ,which accounted for 35.71%,30.52%,26.62%and 7.14%,respectively.The incidence of spinal artery was 66.23%,and 94.12%of which passed through the dorsal nerve root and entered the foramina.The external zones of the thoracic intervertebral foramina were divided into five parts.The amount of secondary branches in the caudal region of nerve roots(CaA)was the largest,with a total of 201(37.43%),while in the dorsal region of nerve roots(DpA),only 11(2.05%)were found.The diameter of spinal artery(SA)was 0.94±0.28(0.32-2.03)mm,and that of dorsal branch(DA)was 1.38±0.33(0.48-2.98)mm.The mean diameter of all secondary branches is 0.59±0.20(0.13-1.31)mm,and the diameters of RA,VA,DpA,CrA and CaA were 0.58±0.22(0.25-1.29)mm,0.67±0.18(0.37-1.02)mm,0.54±0.23(0.32-0.93)mm,0.49±0.16(0.13-1.31)mn,0.65±0.19(0.27-1.33)mm,respectively.Conclusions:The distribution of arteries in the thoracic foramen is very rich.The thoracic extraforaminal arteries is branching in 4 ways,and the occurrence rate of spinal artery is only 66.23%.Secondary arterial branches are most widely distributed in the caudal region of nerve roots,which are the most likely to be injured during surgery.Full understanding of the anatomy of the thoracic extraforaminal arteries is the basis for clinicians to carry out transthoracic foramen techniques. |
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