SP-1 Yinbai (隱白) — Hidden White

On the medial aspect of the distal phalanx of the great toe, at the junction of lines drawn along the medial border and the base of the nail, approximately 0.1 cun from the corner of the nail.

Seated with the feet supported or supine, locate the point on the great toe, at the intersection of the lines passing along the medial margin and the base of the nail.

Skin, subcutaneous tissue, dorsal digital nerve and vein of the medial side of the great toe, crural fascia, dorsal digital branches of the superficial fibular nerve, dorsal digital artery, and the distal phalanx of the great toe.

Perpendicular or proximally directed oblique insertion 0.1–0.2 cun, or prick to bleed with a needle, lancet, or three-edged needle.

Yin (隐), hidden; Bai (白), white. The point lies on the great toe, at the transition between light and dark skin, as if hidden.