[The third component in surgical anatomy and its impacts].

Surgical or local anatomy consists of two components conventionally, organs and their blood supply. In fact, they are enveloped by the fascia membrane and serous membrane. This is the third component in surgical or local anatomy, which is omitted by surgeons for many years. The omitted reasons are failed recognition and unknown function. Re-understanding of the third component in surgical or local anatomy will make some changes in the local anatomy, tumor pathology, oncology surgery and operations. Firstly, the third component makes surgical anatomy developed from organ anatomy, blood vessel anatomy to membrane anatomy, which consists of the mesentery in broad sense and its bed, both include serous membrane and fascia membrane. Secondly, the third component provides the basic membrane anatomy of envelop cavity of metastasis V, and the impairment of its integrity will induce the mesentery cancer leakage of metastasis V in the operation field. Thirdly, based on the development of anatomy and pathology of the third component, cancer of alimentary tract can be divided into 3 types, the cancer in the mesentery, the cancer at the mesentery edge and the cancer outside the mesentery. Cancer outside the mesentery is in the field of oncology except complication of primary lesion, such as bleeding, perforation and obstruction. The main task of surgeons is to prevent the cancer leakage during operation, improve the cancer at the mesentery edge and perform radical operation for the cancer in the mesentery. Finally, the principle of radical operation for the cancer of alimentary tract should include the primary lesion resection, systematical lymphadenectomy and complete mesentery excision. Therefore, these principles should be classified into three kinds:(1) D type operation, which is only the concern about lymphadenectomy at D2 or D3 level and does not care about the completeness of the mesentery; (2) C type operation, which is only the concern about completeness of the mesentery, with only high tie of blood vessels, which does not care about ligation at the bifurcation; (3) D+C type operation, which is not only the concern about ligation at the bifurcation, but also about the completeness of the mesentery. Many aspects will change with surgical developments, especially with the membrane anatomy, the third component.