Morphofunctional features of human extrinsic ocular muscles.

Authors have examined the histoenzymatic features of the human extraocular muscles. Fiber typing was based on myosin ATPase isoenzymes, mitochondrial succinicdehydrogenase and glycogen content. It has been established that the human extrinsic ocular muscles contain all three main types of fibers. Fast fibers with alkali-stable ATPase activity and glycolytic metabolism are mainly present in the ocular muscles and are almost completely type IIa fibers. In addition, in the ocular muscles, slow muscle fibers are less numerous and shorter in diameter. It was not possible to determine the location of different groups of fibers in the specific areas; the anatomical distribution of the various fiber types, in transverse sections, demonstrated a random distribution of all the different types.