The central nervous system (CNS) is the main part of the nervous system, including thespinal cordAnd the brain located in the cranial cavity;It is often located in the middle axis of the animal body, and consists of obvious brain ganglia, nerve cords or brain and spinal cord and the connecting components between them.In the central nervous system, a large number of nerve cells gather together to form a network or circuit organically;Its main function is to transmit, store and process information, generate various psychological activities, and dominate and control all animal behaviors.[3]
Development of central nervous system
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The process of human single fertilized egg developing into an individual is still relatively mysterious to a large extent, because of the complexity of the development process: from a single cell, developing into millions of cells with special functions to tens of billions of cells of mature individuals, and this complex apex is the development of the central nervous system.The central nervous system is formed from the embryonic ectoderm. At the neuroembryonic stage, the notochord is the central axis of the embryo that runs through the embryo at the early stage, inducing the undifferentiated ectoderm cells above it to transform into the primordium of the central nervous system.First, the dorsal ectodermal cells above the notochord elongate and thicken to form a nerve plate that is wide in front and narrow in back;The edge of nerve plate thickens and folds to form nerve folds;The central depression of the nerve plate forms a nerve groove.Then, the nerve fold moves to the midline of the back, and finally closes to form a neural tube. The front of the neural tube develops into a brain, and the back develops into a spinal cord.From this stage, the general characteristics of the brain are determined by the growth and bending of the front of the neural tube.With the gradual enlargement of the cerebral cortex and the generation of cortical folds, a mature brain has been formed. At the early stage of human embryonic development, human fetuses and mammalian fetuses are strikingly similar.This is the general neuroanatomical feature of the development of the central nervous system.[2]
Anatomical observation of peripheral nervous system
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As early as 1906,Bardeen observed the properties of nerve bundle fibers on fetal and adult cadavers, and drew sectional drawings of femoral nerve, obturator nerve and sciatic nerve, marking the areas occupied by main motor and sensory fibers.After the 1940s,Sunderland et al. successively applied the method of microanatomy separation to conduct a comprehensive and systematic study on the formation and arrangement of nerve bundles in the main nerve trunks of the whole body, summarized a set of systematic distribution maps of nerve bundles in the nerve trunks of the limbs, and made a detailed description of the changes of bundle types.Perhaps due to ethnic reasons, the effect of domestic scholars' "following the plan" operation is poor. For this reason, Zhong Shizhen and others in China, according to the needs of peripheral nerve microsurgery technology, combined with the requirements of nerve bundle characterization and positioning, used the acetic acid immersion method to surgically separate and track the nerve bundles and bundle groups in the nerve trunk of adult cadavers under the microscope,The distribution of motor tracts and sensory tracts in the nerve trunk was described with emphasis and regularity, and the local localization map of functional tracts or bundle groups of the main nerve trunk sections in Chinese limbs was drawn.Later, Han Zhen and others proposed a simple method of nerve bundle location based on natural bundle division. The above research results have facilitated clinical application, and played a positive role in clinicians' in-depth understanding of the route and structure of sensorimotor bundles in the peripheral nerve trunk, improving the accuracy of intraoperative nerve alignment, and improving the efficacy of hand surgery.[1]
In 1988, Japaley et al. showed that the arrangement of the peripheral nerve in the proximal segment was very complex and crossed repeatedly, but the distal segment could be separated for a long distance before merging. The significance of the former was that cutting a small number of nerve bundles in the proximal segment of the nerve trunk might not have or have a small impact on the innervation of the nerve,It also provides anatomical basis for Oberlin operation and extended Oberlin operation.The significance of the latter is that a single nerve bundle branch can be further dissociated on the nerve trunk to facilitate the repair of more important nerve bundle branches.The anterior interosseous nerve branch, the pronator teres muscle branch and the flexor carpi radialis branch can be dissociated from the median nerve trunk in the middle and lower arm for repair and transfer.In 2002, Li Shaoguang et al. found through the microanatomy study of the axillary nerve that the axillary nerve can be divided into two bundle groups at the quadrilateral foramen plane, and the bundle group composed of the anterior branch of the axillary nerve innervating the deltoid muscle runs outside the nerve trunk.[1]
The anatomical characteristics of different bundle groups and bundle branches on the nerve trunk provide anatomical basis for improving the therapeutic effect of nerve bundle branch transfer on brachial plexus injury and the selection of nerve bundle groups.[1]
