Applied Anatomy Of Brachial Plexus And Its Main Branches And Three-Dimensional Reconstruction Of Vessels And Nerves In The Upper Limbs

Background:With the development of modern industry and communication, the brachialplexus and its branches injury caused by traumas and road accidents have beenincreasing. It caused serious consequence to society and family with its highmutilation rate. The worst of all is avulsion of brachial plexus and its diagnosis andtreatment has been the focus of hand and traumatic surgery and emphases toresearchers home and abroad. Many scholars have been devoting themselves torecovering the motor function of patients' upper limbs from trying various surgicalmethods and alleviate or remove the complications such as de-input pain. Selectiveposterior rhizotomy and spinal cord implantation of avulsed spinal nerve roots ofbrachial plexus are proper examples. However, the anatomic data concerning theclinical diagnosis and treatment of brachial plexus roots is far away from systematicand comprehensive; especially the report of blood supply of brachial plexus roots.Therefore, it's extremely necessary to conduct the research of micro-dissection ofbrachial plexus roots. The clinical effects of surgical recovery of the brachial plexus and its branchinjury are influenced by many factors, among which blood supply plays an importantrole. There has been a history of more than 200 years about the research of peripheralnerve, PN. It dates back to 1768, it is first time, Isenflamm and Doerffler conductedthe research of the supply blood vessels of PN. Later, using similar methods, manyresearchers summed the data about the blood supply source of the peripheral stemnerve and the volume of received vessels of each nerve. But such research has stillbeen staying at the basic stage for no clinical application is available.Since Taylor made the successful research of vascularised nerve grafts in 1976,the simply basic research of nerve blood supply has converted to clinical application.Meanwhile, the research methods have been improved accordingly. On the basis ofperfusion method, some other methods such as Histology, Kato method by ink, castform by Perchloroethylene, and scanning electron microscope, SEM, etc. had beenused in researching the extrinsic and intrinsic blood supply of PN. But most of themfocu to in the blood supply of cutaneous nerve and there are a few research issuesabout the blood supply of nerve stem of limbs, Systematic data of the blood supplyand classification of nerve stem of limbs are still lack. Besides, PN and thedistribution characteristics of blood supply can't be showed in radiology, it is becausethat the figure of nerves and vessels can't be showed on X-ray film. Therefore, in thissubject, gelatin-lead oxide was used to signify blood vessels, silver nitrate was usedto color the nerve and then radiography was adopted to obtain the angiogram of thenerves in the upper limb. Focusing the blood supply ofbrachial plexus and its mainbranches and meanwhile, the method ofperfused by red latex, Kato method by inkand histological section were used to observe the blood supply of nerves. Differentmethods were compared systematically and completely to show the charateristicas ofnerve blood supply. The evaluation of potential vascularised nerve grafts provides anatomic basis for vascularised nerve grafts and enriches the theory of nerve bloodsupply.With the increasing development of micro-diagnose and treat andThree-dimensional (3D) computerized reconstructions, it is necessary and possible toconduct the 3D-vision research to blood vessel and nerve. Since the 20th century,many countries consumed large amount of workforce and money in Visible HumanVH and made breakthrough successes. Particularly in 2002, anatomists in China useda new method of blood vessel sign technique and reconstructed part of huamn bodyblood vessels by applying it to Virtual Chinese Human, VCH, and made greatcontributions to the development of Chinese Digital Human, CDH. However, atpresent, for CDH, there still exist some difficulties in obtaining nerve message andconstructing the model and it is especially rare in constructing blood vessels andnerves simultaneously. In this subject, the technique of blood vessel and nerve sign,modern technique in image and computer image processing were used to constructthe figure of arm blood vessels and main branches of brachial plexus to show vividlyand objectively the course and adjacent relationship of blood vessels and nerves.Meanwhile, the author is trying to probe a practical method for 3D reconstruction ofthe blood vessel and nerve to provide useful experience to digitizing virtual nervesystem in future.Objectives:1. To provide anatomical basis of diagnose and treatment of brachial plexusroots avulsion.2. To explore the arterial origin and the distribution to the brachial plexus and itsmain branches, and to demonstrate radiographically the topography of the upper limbnerves with their blood supply, and to examine them as an application of theangiosome concept. 3. To reconstruct the three-dimensional structures of the blood vessels andnerves in the upper limb, and to explore a useful and practical method forthree-dimensional reconstruction of the blood vessels and nerves.Methods:1. Macromicrodissection: The morphological features of brachial plexus rootsand the relations between brachial plexus roots and surrounding tissues wereobserved and measured on 15 cervicothoracic spine of adult cadavers, and to observethe arterial origin and distribution to the upper limb nerves under the microscope in10 cadavers embalmed and injected red latex from the common carotid artery.Nutrient artery and source artery of the median nerve, ulnar nerve and ramussuperficialis nerve radialis were measured.2. Transparent and Histology:â‘ The relations between brachial plexus rootsand surrounding tissues were observed on 2 fresh specimens.â‘¡The pattern wasoutlined by intra-arterial injection of colored ink and formaldehyde in 2 limbs freshlyamputated for conditions not affecting the blood vessals or nerves. One nerve wasdissected, removed dehydrated and cleared, and another nerve was removed andstudied. Seven segments, each 3～5cm, in length, were cut from the median and theulnar in the arm and the forearm, the radial nerve, the musculocutaneous nerve, theaxillary nerve. Each segment was fixed in the usual manner and embedded in paraffin.The transverse and longitudinal sections, 150μm, 50μm in thickness respectively, werecut from each block and stained with hematoxylin and eosin.3. Contrast radiography: 3 fresh adult cadaver specimens was perfused with leadoxide-gelatine mixture, dissected the upper limb and dissociated the brachial plexusand its main branches, the main arteries in the upper lamb, 40% silver nitrate creamwas smeared on the median nerve, ulnar nerve, radial nerve, musculocutaneous nerveand axillary nerve, then radiograph and photograph and CT. 4. Digital image process: Because the dimension of a piece of X photo was toolimit to image the whole limbs. So it was necessary to imput it to the computer andmake pictorial synthesis. Thus angiogram of the whole limbs' nerves was formed.5. According to Taylor's angiosome concept and its five kinds of nerve andblood supply, angiosomes of brachial plexus and its major branches were determinedand typing.6. Three-dimensional reconstruction: The images of CT scanning of the upperlimb were digitally analyzed using Amira 3.1 software. Three-dimensional (3D)computerized reconstructions of the main arteries of the upper limb and the mainbranches of brachial plexus were conducted from these data using Amira 3.1software.Results:1. Microanatomy of brachial plexus roots:â‘ The anterior roots were in front ofthe denticulate ligament, while the posterior roots were behind it. The distance fromthe origination of the ventral roots to the midline of spinal cord were 2.2mm for C₅and 3.1mm for T₁, and the length of the brachial plexus roots were 14.9mm, 13.9mmfor C₅ and 21.1mm, 19.0mm for T₁, from up to down, the length increased gradually.On the contrary, the distance from the origination of the posterior roots to the midlineof spinal cord were 4.2mm for C₅ and 2.7mm for T₁, and the angle from the roots tothe spine of C₅～T₁ spine segments were 51.4°,54.8°for C₅ and 21.7°,19.9°forT₁, from up to down, the distance decreased gradually. At the same segment, thediameter of the posterior roots was bigger than the ventral one, C₆ was the biggest.There is complicate fiber association locating on the posterior roots.â‘¡The cranialangle of C₅,C₆ with cord were smaller than that of their anterior ramus, whereas thetrend was reverse in C₇,C₈, T₁.â‘¢The C₅,C₆ nerve roots interlace with tendons ofscalenus anterior and mediscalenus and fuse with the transverse-radicular ligaments in intervertebral foramina, in addition, the lamina fiber liking aponeurosis ofinvestment wrapping up C₅,C₆ nerve roots and vertebral artery, vertebral vein,whereas the case was not seen in C₇,C₈,T₁.â‘£The blood supply of the brachialplexus roots came from segmental arteries of vertebral artery and deep cervical arteryand ascending cervical artery.2. The zonal pattern of blood supply to the brachial plexus: The brachial plexuswas supplied by branches of the subclavian-axillary axis (SAA), and these branchesanastomose each other, according to their distribution feature, the neural territory wasdivided into three zones(angiosomes). The first zone including the nerve roots fromintervertebral foramina to the proximal nerve trunks and this region of the brachialplexus was supplied by direct branches of the subclavian artery(SCA) or branchesoriginating from thyrocervical trunk and costocervical trunk. The second zoneincluding the distal trunks and divisions and the proximal cords was supplied bydirect branches of SCA or branches originating from the dorsal scapular artery(DSA).The DSA was usually thick and contributed to blood supply of a large region. Therewere 2.7(1-5) direct branches of the SCA on the average which have relativelysmaller diameter. The third zone including the distal portion of the cords and theterminal branches of the brachial plexus was supplied by direct branches of theaxillary artery. The mean number of these branches was 3.4(1-6).3. The blood supply of the main branches of brachial plexus:â‘ The arterialsupply of the upper limb nerves came from the adjacent artery including the mainarteries and its branches in the body, it may receive small branches from the vesselswithin muscle or skin and arch of aorta. An epineurial longitudinal arterial systemaccompanies each peripheral nerve and may have "choke zones" and trueanastomoses between long ascending and descending branches of Yshaped arteriaenervorum. When an axial artery accompanies nerves, the nerves tend to be supplied with direct arteriae nervorum. In the absence of such an axial artery, nerves receiveblood supply from either a smaller artery skirting the surface or a fragmented bloodsupply from second- and third-order arterial branches.â‘¡The diameter of the nutrientarteries to the upper limb nerves was no more than 0.8mm and its length was less10mm.â‘¢The blood supply of the upper limb nerves came from uninterruptedangiosomes.â‘£The arterionervous vascularization of the ulnar nervein the upper armand in the forearm, the median nerve in the upper arm and in the forearm, the segmentof anterior interosseous nerve distal to the flexor pollicis longus branch, thesuperficial radial nerve, the terminal branch of posterior interosseous nerve was typeA or C.⑤The blood supply of brachial plexus and its main branches were displayedand observed on specimens by using three methods, but each method had itsadvantage and disadvantage.4. Three-dimensional reconstruction of blood vessel and nerve in the upper limb:3D reconstructed models could perfectly display the spatial relationship of the mainarteries and the main branches of brachial plexus, and rotating in every direction.Conclusions:1. Having an intimate knowledge of microanatomy about brachial plexus rootsin the spinal canal will conduce to diagnose and treatment of brachial plexus rootsavulsion and comprehend mechanism that C₅,C₆ nerve roots of brachial plexus weredifficult to form roots avulsion than C₇,C₈ and T₁ ones.2. The vascular supply of brachial plexus was markedly rich: the vasa nervorumexhibited a tendency to divide into two branches, a distal branch and a proximalbranch. Because the connections between the branches of the vasa nervorum ofteninvolved true anastomoses without changes in caliber, producing a rich longitudinalarrangement of vessels on and within the nerves. This study may help explain howpathological obstruction of major upper limb arteries can sometimes be bypassed with collateral circulation through vasa nervorum within the brachial plexus and provideanatomic base for vascularized brachial plexus transplantation.3. Our work has radiographically depicted the blood supply of the upper limbnerves and shown them to have angiosome territories that match those of thesurrounding composite tissues. Furthermore, we have classified each nerve segmentaccording to its suitability for vascularized nerve transfer, confirming the anatomicalbasis for donor sites already in use and showing other sites whose availabilitydepends on the prevailing clinical circumstances. This work has important clinicalapplications in the reconstruction of nerves of the upper limb.4. Perfusion by red latex was very suitable to study the extrinsic blood supply ofthe peripheral nerve, and Kato method by ink was suitable to show the intrinsic bloodsupply of the peripheral nerve, and contrast radiography method by gelatin-lead oxidewas suitable to display the extrinsic and intrinsic blood supply of the peripheral nerveand study three-dimensional reconstruction of the blood vessels and nerves.5. Since the digitized images of structures of the blood vessels and nerves in theupper limb can offer section by section insights into their anatomies; their 3Dreconstructive models can be applied in clinical training, pre-operative designing andvirtual operation procedures. So we think this is a practical method for 3Dreconstruction of the blood vessel and nerve...