he tibialis anterior muscles on both side of 8 rabbits were studied.According to its fiber architecture, origins. insertion and nerve dis-tribution, the tibialis anterior muscles was divided into two subvolumes :an anterior and a posterior. The muscle samples were taken respectivelyfrom each subvolumes of the tibialis anterior muscles. Frozen transversesections were stained for myosin ATPase. Muscle fibers were identifiedas type , type A and type B. The proportion of fiber types in eachportion and the distributive features in fascicule were calculated on mic-roscopic photographs. Mean cross-sectional areas and mean cross-sectionaldiarneters or three types were measured by imaging analytical system.Theresults showed a remarkably high proportion of type fibers in both theanterior and posterior subvolumes. The type A fibers in anterior subvo-lume comprise about 35.4%, and the type I fibers in posterior subvolumecomprise bout 24.5q% the average occurrence of type B fibers is about50% in both subvolumes, however no difference was found between the leftand right sides. The peripheral part of the fascicule contains 12.7-13.3q%type I fiber and type fiber 59.9-60.0% respectively. The fiber sizebetween type A and type B is similar, but type I fiber is smaller thantype fiber in all portions. The authors suggest that anterior subvolumeas designed to take part in the velocity and dorsiflexion of the foot andthat the posterior subvolume as designed only to stabilize the ankle and tomainta in the arches of foot during standing , running andjumping.