THE NEUROVASCULAR TERRITORIES OF THE SKIN AND MUSCLES - ANATOMIC STUDY AND CLINICAL IMPLICATIONS

In 1987, the results of a series of total-body investigations of the a rterial system of the skin and underlying deep tissues were published. This resulted in the angiosome concept. In 1990, a similar series of studies of the venous network was published. In both investigations, i t was noted that ''vessels hitchhike with nerves.'' This anatomic stud y analyzes these neurovascular relationships in the skin and in the un derlying muscles. Seven fresh human cadavers and nine animals were stu died over a 2-year period. The entire integument of each and a total o f 538 human and 72 animal muscles were removed and analyzed. Either th e arterial or the venous system was injected with a radiopaque lead ox ide mixture, and the dissected nerves were labeled with fine wires, be ing segregated later by a subtraction radiography technique. The resul ts of these investigations are presented, with special emphasis placed on the design of long axial skin flaps placed along neurovascular sys tems and their relationship with the current design of skin flaps. The muscles are classified according to their extrinsic and intrinsic neu rovascular supplies, and suggestions are made as to how they may or ma y not be subdivided into functional units for local and distant transf er. The cutaneous nerves, as well as the motor nerves of the muscles, were invariably accompanied by a longitudinal system of arteries and v eins that often was the dominant supply to the region. Whether the ner ves appeared together with the vessels, whether the nerves crossed the m at an angle, or whether they approached the vessels from opposite di rections, in each case the main trunk of the vessel or some of its bra nches soon ''peeled off'' to course parallel to the nerve. This inform ation provides the basis for the design of long skin flaps placed alon g neurovascular systems. Indeed, it reveals that many of the current ' 'axial'' or ''fasciocutaneous'' skin flaps used in clinical practice a re in fact neurovascular flaps. The muscles are classified into four t ypes according to their extrinsic and intrinsic neurovascular supplies . Type I muscles are supplied by a single unbranched nerve. In type II muscles, the nerve branches before entering the muscle. Type III musc les receive multiple motor nerves from the same nerve trunk, and type IV muscles are supplied from multiple nerve trunks. Suggestions are ma de as to how muscles of each type may or may not be subdivided into fu nctional neurovascular units for local and distant transfer. Our studi es in the pig, monkey, dog, and rabbit reveal that the ''blueprint'' o f the nerves is very similar when the animals are compared with each o ther and with humans. This information may help in planning future stu dies that focus on the neurovascular supply of the tissues in both the adult and the embryo.