General physiology of muscles and nerves . ally twisted, and in the centreof which exists a long rod-shaped kernel or striated muscle, they do not form separate mus-cular masses, but occur scattered, or arranged in moreor less dense layers or strata, in almost all organs.^Arranged in regular order, they very frequently formwidely extending membranes, especially in such tube-shaped structures as the blood-vessels, the intestine, 1 An instance of a considerable accumulation of sfmooth muscle-fibres is afforded by tlie muscle-pouch of birds, which, with the ex-ception of the outer
General physiology of muscles and nerves . ally twisted, and in the centreof which exists a long rod-shaped kernel or striated muscle, they do not form separate mus-cular masses, but occur scattered, or arranged in moreor less dense layers or strata, in almost all organs.^Arranged in regular order, they very frequently formwidely extending membranes, especially in such tube-shaped structures as the blood-vessels, the intestine, 1 An instance of a considerable accumulation of sfmooth muscle-fibres is afforded by tlie muscle-pouch of birds, which, with the ex-ception of the outer and inner skin coverings, consists solely of thesefibres collected in extensive layers. SMOOTH MUSCLE-FIBRES. 97 &c., the walls of which are composed of these smoothmuscle-fibres. In such cases they are usually arrangedin two ]ayers, one of which consists of ring-shaped fibressurrounding the tube, while the other consists of fibresarranged parallel to the tube. When, therefore, thesemuscle-fibres contract, they are able both to reduce.
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Keywords: ., bookcentury1800, bookd, booksubjectmuscles, booksubjectphysiology
