Vascular space that is located in the inguinal ligament and iliac bone between the gap between the medial, and the muscle cavity separated by the iliopubic arch of the structure, within the femoral artery, vein, and deep femoral lymph nodes, etc.; may also refer to the perivascular gap, a kind of normal anatomical structure within the nervous system. 1. Vascular space under the inguinal ligament: it is an important structure for the passage of vascular nerves in the lower limb, located in the medial part of the lower part of the inguinal ligament, surrounded by the inguinal ligament, sickle ligament and other structures. It is surrounded by the inguinal ligament, sickle ligament and other structures, in which the femoral artery, femoral vein, genitofemoral nerve and other important structures are traveling. 2. Perivascular hiatus: the Virchow-Robin cavity (VRS), a normal anatomical structure within the nervous system, has certain physiological and immunological functions. The perivascular space was proposed more than a century ago by the German pathologist R. Virchow and the French biologist and histologist C.P. Robin, and was later named Virchow-Robin cavity (VRS), which is also called perivascular lymphatic space.