Histochemische und morphometrische Untersuchungen der Muskulatur der Vordergliedmaße des Schafes in bezug zu ihrer Funktion: Teil 1. Beuger und Strecker des Ellbogengelenkes

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Muscle tissue was removed from the extensors and flexors of the elbow joint of six male sheep (180 days old) and stained for NADH tetrazolium oxidoreductase and myofibrillar ATPase after preincubation at pH 4.3 in order to identify three fiber types: slow twitch oxidative (STO), fast twitch oxidative (FTO) and fast twitch glycolytic fibers (FTG). The medial head of the M. triceps brachii and the anconaeus muscle had the largest fibers (> 50 and 60 microns). The smallest muscle fibers (35-43 microns) were found in the dorsal part of the long head of the triceps muscle. The medial head of the triceps muscle and the anconaeus muscle possessed a very high percentage of STO-fibers (90 and 100%) and FTG-fibers were absent in these muscles. In the other extensors and flexors of the elbow joint the STO-percentage amounted to less than 30%. The dorsal part of the long head of the triceps muscle contained only 13% STO-fibers, but had the highest percentage of FTG-fibers (49%), which is representative of fast-muscles. The muscles of the elbow joint perform both static and dynamic functions. The medial head of the triceps brachii muscle and the anconaeus muscle possess the complement of enzymes which permits them to fulfil the work of extensors in the standing position. Therefore, they are typical of antigravity muscles. The histochemical structure of the other extensors and flexors reflect their function in motion. The lateral and long head of triceps muscle oppose the flexors and extend the elbow joint of the raised limb in the swing phase, during the landing phase they also function to support the other extensors of the elbow.