[Location] Localized in the erect sitting position or in the upward recumbent position, in the center of the tip of the distal phalanx of the middle finger. (Fig. 7)

[Regional Anatomy] Skin→subcutaneous tissue. The palmar digital proprial nerve of the median nerve, and the arterial and venous network formed by the palmar digital proprial artery and vein. The subcutaneous tissue is full of fasciculus. The fasciculus connect with skin on the superficial aspect, and with the distal phalangx periosteum.