Morphology of diaphragm in the crab-eating monkey (Macaca fascicularis)

Abstract

ABSTRACT. The diaphragm was studied in 30 adult crab-eating monkeys (Macacafascicularis). The muscular bundle of the lumber part was derived from the tendinous origin, which attached to the anterior surface of the lumbar vertebra and intervertebral disc. The upper margin of the origin was at the one third of the second lumbar vertebra in both sides. The lower margin of the right and left tendons extend to lower one third and upper one third of the third lumbar vertebra, respectively. In 22 cases (73.3o7o) out of 30 specimens, some muscular bundles arose from the right crus with the collagenous sheath. They ran across the ventral aspect of the aortic hiatus and bounded the esophageal hiatus at the left side. The muscular fibers, which bound the esophageal hiatus at the right and left, are innervated by ipsilateral phrenic nerve. In four cases, the "Hilfsmuskel" after Treitz was observed. It arose from the connective tissue around the coeliac artery.

Evolution and Functional Differentiation of the Diaphragm Muscle of Mammals

“…In smaller mammals such as rats, mice and hamsters, DIAm fibers extend from their origin at the costal border to insertion at the central tendon, reaching lengths of ~20 mm [162,234,235,245,528], which may be a physiological limit of muscle fiber length. In larger species such as cats, dogs, monkeys and humans, DIAm fibers do not extend the full span between the costal margin and the central tendon but instead, have intramuscular tendinous origins and insertions [59,232,350,466,622]. These differences are evident in the pattern of neuromuscular junction distribution in the DIAm In rodents, neuromuscular junctions are distributed along a clear central line in the middle of the muscle (i.e., at the mid-point of each muscle fiber).…”

“…In rodents this secondary branching pattern is very linear corresponding with the location of neuromuscular junctions. However, in larger mammals there is greater variation and elaboration of secondary branches, corresponding with the wider distribution of neuromuscular junctions [14,59,85,152,350,386,387,443,466,578] (Figure 15). Typically, the DIAm is oriented obliquely in the body, with the origin of fibers in costal and crural regions located more caudally than the origin of fibers in the sternal region.…”