Innervation of the panniculus carnosus in the armadillo, Dasypus novemcinctus

Abstract

There has been considerable recent attention directed at the subject of peripheral nerve-muscle relationship. Probably the concensus of opinion favors the thesis that the Furbringer theory, as originally set forth, is not rigidly applicable. The relationship of a nerve arid its muscle although usually conservative in major respects is not always inflexible. Both variation and evolution in these, as in other anatomical details, can and do occur. There are grounds for believing, too, that afferent pathways are more labile than efferent, and that routes are more variable peripherally than proximally.I n Dasypus novemcinctus it was fouiid that the innervation of the panniculus carnosus was obscured by a diffuse and intricate net-work of nerves on its medial surface. In addition to the anterior thoracic nerve (from the pectoral group), this net-work was contributed to by the spinal nerves. These were of two types analogous to the anterior rami and the lateral rami of the intercostal nerves in man. The former, instead of emerging from the intercostal space close to the sternum, branched from the intercostal nerve more laterally, thus extending directly to the inferomedial aspect of the panniculus.The latter instead of passing through the intercostal space to emerge on the lateral aspect of the thorax, emerged dorsally close to the spinal column and passed laterally and ventrally beneath the trapezius to the dorso-medial aspect of the panniculus.