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Re-investigation of the adult human latissimus dorsi muscle (HLD) by microdissection of acetylcholinesterase (AChE)-stained material revealed a complicated microstructure of this muscle. Motor endplates distribute over the entire muscle; numerous AChE-stained myomyonal and myotendinous junctions are interspersed. After teasing muscle fascicles from selected representative areas, the following results were obtained. Most of the single muscle fibers constituting the fascicles are shorter than the length of the fascicles. They are linked together by myomyonal junctions or by myotendinous intersections end-to-end, end-to-side, or via muscular crossbridges side-to-side, thus forming chains and nets of varying appearance and length. Additionally, many fiber furcations were found. These observations throw light on the microarchitectural basis of local mass changes of the triangular HLD occurring during its convergence from its wide lumbar and thoracic attachment line to its narrow tendon attached to the humeral crista tuberculi minoris. The microstructural observations also explain why motor endplates spread over the whole muscle, instead of being restricted to a single central endplate-band, as is found in the majority of other muscles. To clarify postnatal development, the topography of endplates in adult muscles was compared with fetal and infantile muscles. Primarily, the endplate bands were clearly demarcated; their width then broadened, and they gradually scattered into groups of single endplates. Simultaneous with these developmental changes, a corresponding branching of the thoracodorsal nerve occurs.

Our research work concerns the definition of computational systems for the solution of complex scientific problems. In this work we present the analysis of a computing model for the definition and the implementation of microprogrammed prototypal machines. The computing model is expressed in terms of a system of equations. The structure and the control of a microprogrammed machine is directly implied by the formally defined properties of the system of equations.