The angiosomes of the forearm: anatomic study and clinical implications.

The angiosome concept was introduced in 1987 by Taylor and Palmer. Their anatomic study correlated the blood supply to the skin from the named segmental or distributing "source" arteries with their supply to the underlying muscles, tendons, nerves, and bones. Although this investigation encompassed the body, there were areas where the supply to individual tissues was not examined in detail. The present study, therefore, examines one of these regions where certain voids in our knowledge still exist--the forearm. Ten upper limbs from fresh cadavers were studied over an 18-month period after perfusing each with a radiopaque lead oxide mixture. The arterial supply to the skin and the bones of the forearm, together with that of a total of 200 muscles, was examined. The contribution to each was defined by dissection, by metal clip tagging of vessels, by radiography, and by mapping the branches with colored pins coded to match the respective source arteries. In the case of the muscles, a subtraction technique was used whereby the bones of the extremity were replaced with radiolucent balloons to obtain an unobscured picture of the forearm vasculature. Then the muscles were removed one by one from the muscle mass and x-rayed again. In this way, the angiosomes in the forearm, provided by the brachial, radial, ulnar, and interosseous arteries, were defined. Similarly, the contribution from each angiosome to the skin, to each muscle, and to the radius and the ulna was identified and the territories were color-coded to match these source arteries. Results showed that in most cases the connections between adjacent angiosomes occurred within tissues, not between them. The skin, the bones, and most muscles received branches from the source arteries of at least two angiosomes, thus revealing one of the important anastomotic pathways by which the circulation is reconstituted in those cases where a source artery is interrupted by disease or trauma. Several muscles, however, were supplied within one angiosome. This helps explain the variable clinical pictures seen in cases where the circulation is interrupted, such as that which occurs in a Volkmann's ischemic contracture. Finally, this anatomic study provides further information to help design various flaps from the forearm for local or free transfer. In the case of muscles, the supply to most from multiple angiosomes allows for refinements whereby a portion only of a muscle can be used. Similarly, this anatomic information reveals the pathway by which the supply to remaining muscle groups is reconstituted when one of the source arteries is harvested with a skin flap, a muscle, or part thereof.