OBJECTIVETo provide appropriate needling angle and depth for the acupuncture and acupoint injection at Neiguan (PC 6), and to avoid damaging nerves and vessels so as to produce its maximum effect.

METHODSThirty adults' upper-limb samples were used to dissect and observe the referred hierarchical structure and adjoining crucially nerves and vessels in needling Neiguan (PC 6) according to the national standard Acupoint Location (GB 12346-90).

RESULTSIn this punctuation region, there are three parts rich in connective tissues containing the nerves and blood vessels. The surface part is between the skin and the musculus flexor digitorum superficialis and it is the tissue which contains medial and lateral antebrachial cutaneous nerve and its nutrient artery. The middle part is between the musculus flexor digitorum superficialis and the flexor digitorum profundus muscle and contains the median nerve, its palmar branch of and artery. The deep part is between the pronator quadratus muscle and the interosseous membrane and contains the anterior interosseous nerve. When perpendicular needling, the depth of needling the body from skin to the superficial surface of the musculus flexor digitorum superficialis and to the superficial surface of the flexor digitorum profundus muscle is (6.68 +/- 0.64) mm and (12.37 +/- 0.87) mm respectively. The depth of needling the body from skin to the superficial surface of the pronator quadratus muscle and to the superficial surface of the anterior interosseous terminal branch of the nerves is (17.83 +/- 1.00) mm and (30.87 +/- 1.85) mm respectively, and the proportional cun is (2.20 +/- 0.14) cm. The ulnaris cord of median nerves are located at the radial of the needle. The deep layers could touch the anterior interosseous nerve ending.

CONCLUSIONPerpendicularly needling Neiguan (PC 6) for 3 fen (6.68 mm), 5 fen (12.37 mm) and 1.4 cun (30.87 mm) will stimulate the nervus vascularis of the rich part of surface, middle and deep connective tissues respectively and produce the acupuncture effect. During the acupoint injection, perforating the needle perpendicularly at the middle point of the two tendons or deviating slightly to the direction of tendon of palmaris longus can avoid the damage of the median nerve cord.